Samples for analysis shall be taken from Official Samples which have been taken and packed in the manner prescribed in the Fertilizers and Animal Foodstuffs (Sampling) Rules, 1972.

The following apparatus shall be used in the preparation of a sample for analysis—

If the Official Sample is in a fine condition and passes through a sieve having apertures about 1 mm square it shall be thoroughly mixed and a portion not less than 250 gm in weight shall be placed in a storage bottle. From this portion the quantities for analysis shall be taken.

If the Official Sample does not wholly pass through the sieve having apertures about 1 mm square, and wholly passes through the sieve having apertures between 2 and 3 mm square or if a change in a moisture content is likely to occur during the preparation of the Official Sample for analysis, the Official Sample shall be thoroughly mixed and a portion for the determination of moisture shall be taken at once.

If the Official Sample is in a coarse condition (but can be pulverized) as, for example, pieces of broken cake, it shall be carefully pulverized until the whole passes through the sieve having apertures between 2 and 3 mm square. It shall then be thoroughly mixed and a portion for the determination of moisture shall be taken at once.

Material which does not admit of being pulverized in its natural condition so that it will pass through the sieve having apertures between 2 and 3 mm square shall be mixed as thoroughly as its condition will allow. A portion of the coarse material shall then be taken for the determination of moisture and if the dry material can be pulverized, sufficient of the coarse material to produce at least 250 g of dried material shall similarly be dried and then pulverized, so that it will pass through the aforesaid sieve. It shall then be thoroughly mixed. A portion of the material which has been prepared in the manner prescribed in rules 3(1), 3(2), 3(3) and 3(4) of this rule weighing not less than 250 g shall then be taken and if necessary further pulverized until it passes through the sieve having apertures about 1 mm square. The portion of the sample so prepared shall be placed in a storage bottle and from it the quantities for analysis shall be taken.

If the Official Sample is a liquid, it shall be placed in a storage bottle and shall be well stirred immediately before each sample is taken for analysis.

For a grading analysis, the sample shall be taken direct from the Official Sample.

Fertilizers or animal foodstuffs which separate readily into separate fractions which are not susceptible to mixing together during preparation for analysis shall be separated into their component fractions, each fraction shall be analysed as if it was a separate fertilizer or animal foodstuffs and the proportion of the separate fractions shall be allowed for in reporting the analysis.

The moisture content of material which gains or loses moisture during its preparation for analysis shall be determined on a sample of the material which has been prepared for analysis each time a sample is taken for analysis.

Any change in moisture content during preparation of the sample shall be allowed for in presenting the results of analysis.

The samples taken for analysis and for moisture determination shall be drawn in as equal portion as possible from several well scattered points in the material which has been prepared for analysis or whose moisture content is being determined.

The following apparatus shall be used for the determination of moisture in a fertilizer or in an animal foodstuff where the sample tested is deemed by the analyst to be suitable for drying at 100°C—

About 5 grams of the sample (or the minimum larger amount that, with regard to its coarseness, the analyst shall consider to be representative of the sample), weighed to the nearest milligram shall be heated in the oven for 2 to 3 hours. The sample shall then be placed in the desiccator to cool and shall then be re-weighed, again to the nearest milligram. The heating, cooling and weighing process shall be repeated until the difference in weight before and after heating is less than 5 mg. The percentage moisture shall be taken as the total loss in weight as a result of the heating process, in milligrams, multiplied by 100 and divided by the weight also in milligrams of the sample taken for the moisture determination.

Where the sample is deemed by the analyst to be of a nature unsuitable for drying at 100°C, he may undertake the drying at a reduced pressure and at a much lower temperature as is compatible with the stability of the product and he may utilize phosphorus pentoxide or some other desiccating agent to assist the process, or he may employ any other method which is suited to the determination of the moisture content of the sample and he may use such specialized apparatus as the method may require. In these circumstances the moisture content reported shall be qualified by an indication of the method employed.

The following apparatus and reagents shall be used for the determination of oil in an animal foodstuff—

Between 3 and 5 gm weighed to the nearest milligram, of the analysis sample shall be placed in the extraction thimble and this shall then be placed in the extraction apparatus. The extraction apparatus shall then be fitted with a receiving flask into which has been placed about 100 ml of the petroleum spirit. The apparatus so assembled shall be heated for a total of 16 hours in the heater unit the heat control being kept so adjusted that condensate falls from the reflux condenser into the extraction apparatus throughout that time at the rate of 5 or 6 drops per second. The bulk of the petroleum spirit in the receiving flask shall then be distilled through the distillation condenser into the distillate receiver and the flask shall then be heated in the oven for 30 minutes, placed in the desiccator to cool and weighed to the nearest milligram. The heating, cooling and weighing process shall be repeated until the difference in weight of the receiving flask and its contents before and after heating is less than 3 mg. The percentage oil found shall be taken as the weight of the residue in the receiving flask in milligrams, multiplied by 100 and divided by the weight also in milligrams of sample taken for the analysis. Where an allowance for change in moisture content under rule 2(c) of these Rules must be made, the percentage oil reported shall be the percentage found divided by (100–the percentage moisture content of the sample determined as prescribed in rule 2(a) of these Rules) and multiplied by (100–the percentage moisture content of the Official Sample). Otherwise the percentage found shall be the percentage reported.

The following apparatus and reagents shall be used for the determination of fibre in an animal foodstuff—

A small weighed portion of the sample which has been prepared for analysis in the manner prescribed in rule 2 of these Rules, shall be heated with an excess of the 1 per cent hydrochloric acid.

If no effervescence is observed, between 2.7 and 3.0 gm, of the sample which has been prepared for analysis in the manner prescribed in rule 2 of these Rules shall be taken and weighed to the nearest milligram.

The weighed sample shall be extracted with the petroleum spirit in the manner prescribed in rule 6 of these Rules or by stirring, settling and decanting three times with the petroleum spirit in a small beaker. The sample shall in no manner be ground in the extraction process. The extracted sample shall be air-dried and transferred to a 400 ml beaker. Sufficient of the 0.255N sulphuric acid to fill the flask to its 200 ml mark shall then be heated to its boiling point. 30 to 40 ml of this solution shall then immediately be added to the extracted sample.

The beaker shall be gently swirled to disperse the sample. Sufficient of the heated sulphuric acid solution shall then immediately be added to fill the beaker to the 200 ml mark. The beaker and its contents shall be heated on the hot plate so that they come to the boil within 1 minute. The boiling shall then be continued gently for exactly 30 minutes. During boiling the beaker shall be swirled every few minutes in order to mix the contents and remove particles from the sides. Meanwhile the Buchner funnel shall be prepared by placing a muslin cloth over the holes of the plate. The Buchner funnel shall then be fitted in the suction flask and boiling water shall be poured into the funnel and this shall be allowed to remain in the funnel until the funnel is hot. The hot water shall then be drawn away by the application of suction. At the end of the 30 minutes of boiling the beaker shall be removed from the hot plate and the acid mixture poured at once into a shallow layer of hot water which is under gentle suction in the prepared funnel. The suction shall then be so adjusted that the filtration of the bulk of the 200 ml of acid mixture is completed within 10 minutes. If the filtration takes longer than 10 minutes, the determination shall be discarded and a new determination shall be undertaken. The residues from the sulphuric acid extraction shall then be washed with boiling water until the washings are free from acid. Sufficient of the 0.313N solution of sodium hydroxide to fill the beaker to the 200 ml mark shall be brought to boiling point in an insulated wash bottle and some of it shall be used to wash the residue on the muslin cloth and in the funnel back into a 400 ml beaker. Sufficient of the hot sodium hydroxide solution shall then immediately be added to fill the beaker to its 200 ml mark. The beaker shall then be put on the hot plate and again heated so that its contents come to the boil within 1 minute. Boiling shall then be continued gently and continuously for exactly 30 minutes. During boiling the beaker again shall be swirled every few minutes in order to mix its contents and remove particles from the sides. At the end of this 30-minute boiling period, the beaker shall be removed from the hot plate and its contents shall be transferred to a muslin cloth in a 15 cm filter funnel. Any insoluble material remaining in the beaker shall be transferred to the muslin cloth by washing with boiling water and the residue shall then be well washed on the muslin cloth with boiling water. The residue shall then be washed with the 1 per cent hydrochloric acid solution. The residue shall then be rewashed with boiling water until it is free from acid. The residue shall then be washed twice with the 95 per cent alcohol and three times with the diethylether. The residue on the muslin cloth shall be transferred with diethylether to a weighed dried silica dish whose weight shall have been determined to the nearest milligram. The silica dish and its contents shall then be heated in the oven for 30 minutes, placed in the desiccator to cool and weighed to the nearest milligram. The heating, cooling and weighing process shall be repeated until the difference in weight before and after heating is less than 3 mgm. The silica dish and its contents shall then be placed in the silica capsule and the capsule and its contents shall be placed in the furnace, the furnace then being cool. The furnace and its contents shall then be heated until the contents of the silica capsule are incinerated, but the temperature inside the furnace during that time shall not be allowed to exceed 600°C. The capsule and its incinerated content shall be placed in the desiccator to cool and shall then be reweighed to the nearest milligram. The amount whereby the weight of the silica dish and its contents after the incineration exceeds the known weight of the said silica dish, empty, shall be taken as the weight of ash in the residue. The apparent fibre content of the sample shall be taken as the amount whereby the weight of dry residue collected on the muslin cloth exceeds the weight of ash in the residue. The actual fibre content multiplied by the factor (0.0102t—0.02), where ‘t’ is the observed boiling point of water in °C in the laboratory at which the determination was carried out. The percentage fibre found shall be taken as the actual fibre content so found in milligrams, multiplied by 100 and divided by the weight also in milligrams, of sample taken for analysis. Where an allowance for change in moisture content under rule 2 of these Rules must be made, the percentage fibre reported shall be the percentage found, divided (100—the percentage moisture content of the sample determined as prescribed in rule 2(b) of these Rules) and multiplied by (100—the percentage moisture content of the Official Sample). Otherwise the percentage found shall be the percentage reported.

If an effervesence is observed in application of the test prescribed in section (a) of this rule, the suspension shall be stirred well and allowed to settle. The supernatant liquid shall be decanted through a 12.5 cm general purpose filter paper of known weight in an 8 cm filter funnel and the residue shall be washed twice and then transferred to the filter paper. The residue and the filter paper shall then be dried in the oven and reweighed.

The quantity of the sample taken for the test in accordance with these Rules which would be sufficient to give 2.7 gm and 3.0 gm respectively of residue after treatment in the manner prescribed in rule 6(b) of this rule shall then be calculated.

A quantity of the sample which has been prepared for analysis in the manner prescribed in rule 2 of these Rules which shall be between the weights calculated in rule 6(7) of this rule shall then be taken and weighed to the nearest milligram. The weighed sample shall then be extracted with the petroleum spirit in the manner prescribed in rule 6(4) of this rule and transferred to the 400 ml beaker. The extract sample shall then be treated in the beaker with an excess of the 1 per cent hydrochloric acid and the suspension shall be agitated well and allowed to settle. The supernatant liquid shall be decanted through a muslin cloth in an 8 cm filter funnel. The residue shall then be washed twice with water by decantation through muslin cloth. The residue in the beaker and on the muslin cloth shall then be allowed to drain thoroughly. Sufficient of the 0.255N sulphuric acid to fill the 400 ml beaker to its 200 ml mark shall then be heated to its boiling point and 30 to 40 ml of the hot acid shall be used to wash any particles on the muslin cloth back into the beaker. The fibre determination shall then proceed in the manner prescribed in rule 6(5) of this rule.

The following apparatus and reagents shall be used for the determination of nitrogen in a fertilizer or in an animal foodstuff—

The following apparatus and reagents in addition to those specified in paragraph (1) of this rule shall be used for determination of nitrogen in a fertilizer in which nitrogen is declared to be present only in organic and ammonium forms or protein in an animal foodstuff—

About 2 gm, weighed to the nearest milligram, of the sample which has been prepared for analysis in the manner prescribed in rule 2(a) of these Rules shall be placed in a Kjeldahl flask and to it shall be added 25 ml, measured by measuring a cylinder, of the concentrated sulphuric acid. The flask then shall be gently heated until frothing ceases. If frothing is excessive 0.5 gm of the paraffin wax shall also be added.

10 gm of potassium sulphate or anhydrous sodium sulphate and 0.5 gm of the copper sulphate or elemental selenium shall then be added and the flask strongly heated until the colour of the clear liquid ultimately obtained ceases to diminish. Heating shall then continue for a further one and a half hours. The contents of the Kjeldahl flask shall then be allowed to cool and water shall be added, at first in small quantities with further intervals of cooling of the flask as necessary, until a total volume of about 250 ml is obtained. A piece of litmus paper shall then be placed in the diluted solution and, with swirling of the flask to ensure mixing, the 50 per cent solution of sodium hydroxide shall be added slowly until the litmus paper just turns blue. A further 10 ml, measured by measuring cylinder of the sodium hydroxide solution shall then be poured carefully down the side of the flask so that it does not mix at once with the other constituents of the flask. The flask shall then at once be mounted in a heater unit and connected to the ammonia distillation apparatus, the outlet shall dip into a measured volume of standard sulphuric or hydrochloric acid, in a 500 ml flat bottom flask. The amount and normality of standard acid into which the ammonia distillation apparatus outlet shall dip shall be determined by the amount of nitrogen which the fertilizer or the amount of crude protein which the animal foodstuff is believed to contain and shall be in accordance with the following table—

The following apparatus and reagents shall be used for the determination of phosphate in a fertilizer or in an animal foodstuff—

The following apparatus and reagents in addition to those specified above shall be used for the determination of water soluble phosphate in a fertilizer—

Between 9.9 and 10.1 gm, weighed to the nearest milligram, of the sample which has been prepared for analysis in the manner prescribed in rule 2(a) of these Rules, shall be transferred to a 500 ml volumetric flask. 400 ml of water at 20°C shall then be added and the flask shall be shaken continuously for 30 minutes on the shaking machine. The contents shall then be diluted to volume, mixed well and filtered through a dry 32 cm filter paper in the dry filter funnel into the dry flat bottom flask.

25 ml measured by pipette, of the filtrate shall be transferred to the 50 ml beaker and to it shall be added by safety pipette, 1 ml of the concentrated nitric acid. The solution shall then be heated to incipient boiling on the hot plate and maintained at this temperature for 10 minutes. It shall then be cooled, a piece of litmus paper shall be placed in the solution and approximately 1.0N sodium hydroxide solution shall be added slowly, with stirring, until the paper starts to turn blue. The solution shall then be transferred to a 50 ml volumetric flask and diluted to volume.

This solution shall then be further diluted with water at 20°C to an extent which shall be determined by the percentage of phosphorus pentoxide which is believed to be present in accordance with the following table—

The following apparatus and reagents in addition to those specified under rule 8(1) of these Rules shall be used for the determination of total phosphorus pentoxide in a mineral fertilizer—

Between 4.9 and 5.1 gm weighed to the nearest milligram of the sample which has been prepared for analysis in the manner prescribed in rule 2(a) of these Rules shall be placed in the 400 ml beaker. 100 ml of water shall be added and the whole shall be stirred thoroughly. The mixture shall then be brought to the boil and to the boiling liquid shall be added by safety pipette, 10 ml of the concentrated hydrochloric acid in a fine stream and then 10 ml of the concentrated nitric acid. The mixture shall continue to be boiled for 10 minutes and shall then be cooled, transferred to the 500 ml volumetric flask and diluted to volume at 20°C with distilled water. The contents of the flask shall be mixed well and filtered through a dry filter paper in the dry filter funnel into the dry flat bottom flask, the first 10 to 20 ml of filtrate being discarded.

The phosphate determination shall then proceed in the manner prescribed in subsections (b)(iv), (v), (vi), (vii), (viii) and (c)(v) of this rule.

The following apparatus and reagents in addition to those specified under rule 8(1) of these Rules shall be used for the determination of total phosphate in a fertilizer containing organic material or in an animal foodstuff—

Between 4.9 and 5.1 gm weighed to the nearest milligram of the sample which has been prepared in the manner prescribed under these Rules shall be placed in the silica capsule or dish. 1 gm of calcium oxide shall then be added and mixed with the sample and the mixture shall be thoroughly wetted with water. The wet mixture shall then be dried in the oven. It shall then be heated gently and finally incinerated in the furnace to destroy as much organic matter as possible, but the temperature in the furnace during that time shall not be allowed to exceed 500°C.

The incinerated material shall then be allowed to cool and shall be transferred to the 400 ml beaker with 10 ml of distilled water. 12 ml of the concentrated hydrochloric acid shall then be added, the addition being made sufficiently slowly to avoid loss by effervescence. 5 ml of the concentrated nitric acid shall then be added. The mixture shall then be heated to incipient boiling and kept at that temperature for 10 minutes. About 10 ml of water shall then be added and the solution filtered through a 12.5 cm filter paper in an 8 cm filter funnel into a 400 ml beaker, any insoluble material remaining being transferred to the filter with minimum amount of water and washed twice with small quantities of water. The filtrate on the beaker shall then be protected with the watch glass.

The filter paper and the insoluble matter it contains shall then be transferred to the original capsule or dish and dried in the oven. It shall then be heated gently and finally incinerated in furnace, the incineration being continued until all the carbon is destroyed, but the temperature in the furnace during that time shall not be allowed to exceed 500°C.

The resultant ash shall then be combined with the filtrate which had been protected with the watch glass in a beaker and the whole shall be heated to boiling. The solution shall then be cooled to 20°C, transferred to a 500 ml volumetric flask diluted to volume, mixed well and filtered through a dry 32 cm filter paper in the dry 20 cm filter funnel into the dry flat bottom flask, the first 10 to 20 ml of filtrate being discarded.

The phosphate determination shall then proceed in the manner prescribed under this rule.

The following apparatus shall be used for the determination of the percentage material passing through a Standard Test sieve—

A large portion of the Official Sample shall be mixed thoroughly on the hardwood surface and a representative portion thereof obtained by applying the procedure prescribed under rule 15 of the Fertilizer and Animal Foodstuffs (Sampling) Rules, 1972 (L.N. 214/1972), for obtaining a sub-sample and weighting at least 25 gm, shall be dried at 100°C and cooled. About 20 gm, weighed to the nearest centigram, of the dried sample shall be transferred to the sieve with the lower receiver attached. The lid shall then be fitted and the sieve shall then be shaken for five minutes with frequent tapping of the sides. The powder which collects in the lower receiver during the shaking shall then be brushed with the flat brush into the small weighed beaker and weighed to the nearest centigram. The sieving unit shall then be reassembled and shaking and tapping shall be continued for two minutes. The powder which has collected in the lower receiver during this second shaking period shall then be added to the first portion and the weighing repeated. The shaking, tapping and weighing processes shall be continued until no more than four centigrams of powder passes through the sieve in a two-minute shaking period.

The fibres of the dabbing brush shall be applied to any lumps remaining on the sieve after each shaking period so as to cause them to disintegrate but care shall be taken that the hard parts of the brush do not make contact with the lumps during the disintegration or that the brush is not used to brush particles through the sieve.

The percentage material reported as passing through the sieve shall be taken as the total weight of powder in centigrams collected in the lower receiver, divided by the weight in grams and parts of a gram of dried sample taken for the determination.

The following apparatus and reagents shall be used for the determination of free acid in Sulphate of ammonia—

Any insoluble matter retained in the filter shall be washed repeatedly and the combined filtrate and washing shall be made up to about 250 ml. This solution shall then be titrated from a burette of suitable capacity with the standard sodium hydroxide, using two or three drops of methyl red solution as indicator, the titration being made to the nearest 0.05 ml. The per cent free acid found in the fertilizer shall be taken as the number of millilitres and parts of a millilitre, of the standard sodium hydroxide solution used to neutralize the fertilizer solution, multiplied by 4.0 times the normality of the aforesaid standard sodium hydroxide solution and divided by the weight in grams and parts of a gram of sample taken for the analysis.

Where an allowance for change in moisture content under these Rules must be made, the percentage free acid content reported shall be the percentage found divided by 100 minus the percentage moisture content of the sample determined as prescribed under these Rules and multiplied by 100 minus the percentage moisture content of the Official Sample. Otherwise the percentage found shall be the percentage reported.

The following apparatus and reagents shall be used for the determination of biuret in a urea containing fertilizer—

A portion of the sample which has been prepared in the manner prescribed under these Rules and which is believed to contain between 0.4 and 1.2 gm of biuret shall be weighed to the nearest decigram.

The portion taken shall be placed in the litre beaker, together with 700 ml of distilled water. The mixture shall be heated to 70° to 80°C with stirring and then allowed to cool to 30°C. A piece of litmus paper shall then be added and the solution shall be neutralized with the approximately 0.1N sodium hydroxide (if the paper turns red) or the approximately 0.1N sulphuric acid (if the paper turns blue) until the paper just starts to change colour. The solution shall then be filtered into the 1,000 ml volumetric flask. The residue shall be washed three times with water and the combined washings and filtrate diluted to volume.

50 ml of the samples solution so obtained shall be measured by pipette into a 100 ml volumetric flask.

About 2 gm, weighed to the nearest milligram, of the pure biuret shall be treated in the manner prescribed in this rule.

Into a series of six 100 ml volumetric flasks shall be measured by burette, 10.0, 14.0, 18.0, 22.0, 26.0 and 30.0 ml of the pure biuret solution so obtained. The total volume of each of the pure biuret solutions shall then be adjusted to 50 ml by suitable addition of water from a second burette.

To each of these 50 ml samples of pure biuret solution and to the 50 ml aliquot of sample solution, 20 ml of the sodium potassium tartarate solution and 20 ml of the copper sulphate solution shall be added with constant swirling. The solutions shall then be diluted to volume and stood for 15 to 30 minutes in the water bath at between 32.9°C and 33.1°C while their colour develops. While the solutions are standing in the water bath the spectrophotometer shall be set to operate at 5500A° (or the colorimeter or absorptiometer shall be brought into operation as the case may be). Then, the standing period having been completed and following the procedures which are appropriate to the operation of the instrument used, the optical densities of its cells be compared, using the coloured standard solution containing 10.0 ml of the pure biuret solution. If the comparison reveals that there is a small difference between the two cells being used, the cell with the lower optical density shall be used as the standard reference cell. The apparent optical densities of the coloured standard solutions and of the coloured sample solution relative to the coloured standard containing 10.0 ml of pure biuret solution per 100 ml shall then be determined.

The apparent optical densities of the coloured standard solution shall be plotted on a calibration graph against the number of millilitres of pure biuret solution per 100 ml which they contain. The number of millilitres of pure biuret solution per 100 ml in a coloured standard solution having the same optical density as the coloured sample solution shall then be determined by interpolation on the calibration graph. The determination shall be made to the nearest millilitre.

A new pure biuret solution, a new set of coloured standards prepared from it and a new calibration graph shall be prepared for each biuret determination.

If the number of millilitres of pure biuret solution per 100 ml of a coloured standard solution having the same optical density as the coloured sample solution is expressed at x, and the number of grams and parts of a gram of pure biuret which was weighed out for preparing the pure biuret solution is expressed as y, the percentage biuret found in the fertilizer shall be taken as x times y multiplied by 2 and divided by the weight in grams and parts of a gram of sample taken for the analysis.

Where an allowance for change in moisture content under these Rules must be made, the percentage biuret reported shall be the percentage found, divided by 100 minus the percentage moisture content of the sample determined as prescribed under these Rules and multiplied by 100 minus the percentage moisture content of the Official Sample. Otherwise the percentage found shall be the percentage reported.

The following apparatus and reagents shall be used for the determination of salt in an animal foodstuff—

About 5 gm weighed to the nearest milligram of the sample which has been prepared in the manner prescribed under these Rules shall be placed in the silica dish. 1 gm of the calcium oxide shall then be added and shall be mixed with the sample and the mixture shall be wetted with water to a thick paste. The mixture shall be dried in the oven, allowed to cool and then ground to a fine powder and shall then be heated gently and finally incinerated in the furnace until all the organic matter has been thoroughly charred, but the temperature in the furnace during that time shall not be allowed to exceed 500°C.

The residue shall then be extracted with repeated portions of hot water and filtered through a general filter paper. The filtrate shall be cooled and diluted to volume in a 250 ml volumetric flask. 100 ml of this solution shall be measured by pipette into the conical flask and acidified with the dilute nitric acid. A known volume of the 0.1N silver nitrate solution shall then be measured into the solution in the conical flask from a burette, the silver nitrate solution being added until no further precipitate is formed and a slight excess of silver nitrate is present. The volume of 0.1N silver nitrate added shall be measured to the nearest 0.1 ml. The precipitate shall then be stirred well, filtered through a rapid filter paper into the flat bottom flask and washed thoroughly. 5 ml measured by pipette, of the ferric indicator solution and a few millilitres of the clarified nitric acid solution shall then be added to the combined filtrate and washings in the flat bottom flask. The excess of the silver nitrate remaining in the filtrate shall then be determined by titration with 0.1N ammonium or potassium thiocyanate from a burette until a permanent light brown colour appears. The titration shall be made to the nearest 0.1 ml.

If the number of millilitres and parts of a millilitre of 0.1N silver nitrate added to the solution in the conical flask is expressed as x and if the number of millilitres and parts of a millilitre of 0.1N thiocyanate solution used in the titration to determine the excess of silver nitrate is expressed as y, the percentage salt found be taken as x-y multiplied by 1.461 and divided by the weight in grams and parts of a gram of sample taken for the analysis.

Where an allowance for change in moisture content under these Rules must be made, the percentage salt reported shall be the percentage found, divided by 100 minus the percentage moisture content of the sample determined as prescribed under these Rules and multiplied by 100 minus the percentage moisture content of the Official Sample. Otherwise the percentage found shall be the percentage reported.

The following apparatus and reagents shall be used for the determination of ash, sand, silicious material and other insoluble mineral matter in an animal foodstuff—

Between 2 and 5 g weighed to the nearest milligram of the sample which has been prepared in the manner prescribed under these Rules shall be placed in a silica capsule or dish and shall then be heated gently and finally incinerated in the furnace until all the carbon has been destroyed but the temperature in the furnace during that time shall not be allowed to exceed 500°C. The ash shall then be cooled and moistened with the concentrated hydrochloric acid. The moist ash shall then be evaporated to dryness and baked on the hot plate. The dried ash shall then be extracted repeatedly with the hot dilute hydrochloric acid. The extract each time shall be decanted through a filter paper in the filter funnel. After the extraction has been completed, the residue shall be transferred to the aforesaid filter paper in the filter funnel and shall be washed thoroughly with hot water. The filter paper and the residue it contains shall then be placed in a silica capsule or dish whose weight is known to the nearest milligram. These shall be dried in the oven, and shall then be heated gently and finally incinerated in the furnace until all the carbon is destroyed, but the temperature in the furnace during that time shall not be allowed to exceed 500°C. The silica capsule and the ash it contains shall be allowed to cool and shall be reweighed, the weight being determined to the nearest milligram. The percentage of sand, silicious matter and other insoluble mineral material found shall be taken as the weight in milligrams of ash so found, multiplied by 100 and divided by the weight in milligrams of samples taken for analysis.

Where an allowance for change in moisture content under these Rules must be made, the percentage of sand, silicious material and other insoluble matter reported shall be the percentage found, divided by 100 minus the percentage moisture content of the sample determined as prescribed under these Rules and multiplied by 100 minus the percentage moisture content of the Official Sample. Otherwise the percentage found shall be the percentage reported.

In addition to the declaration and warranty required to be given by vendor under rule 2 of these Rules, the vendor shall in respect of each kind of approved fertilizer involved in the transaction make a separate declaration in writing as follows—

Where the vendor is selling an approved fertilizer partly or wholly by virtue of the contents of its constituents in respect of which he is required to make a declaration and warranty under rule 5 of these Rules, he shall in addition give to the purchaser the following guarantee—

In the declaration and warranty, the vendor shall insert in the spaces kept blank for the purpose of the following particulars—

The Inspector drawing an Official Sample shall affix to each container or package containing such Official Sample a certificate signed by himself and stating—

He shall then despatch one Official Sample, with the Certificate attached, to an analyst appointed under section 8 of this Act and one under registered cover to the person holding the fertilizer or animal foodstuffs for sale or who last sold the fertilizer or animal foodstuff and shall forward the third sample to the Government chemist.

For the purposes of sections 4 and 5 of the Act any bone, bones or other substances of animal origin imported into Kenya or used for the purpose of manufacturing any fertilizer or animal foodstuff shall have been sterilized by—

After sterilization every precaution shall be taken to prevent reinfection of the sterilization product and it shall be packed at the factory in new bags.

No vehicle, vessel or barge which has been used for the conveyance of unsterilized bones or other substances derived from animal carcasses shall be used for the transport of sterilized animal products unless it has been first disinfected with a disinfectant solution equal in disinfective value to a 5 per cent solution of standard phenol.