SAMPLES Fdi; ANALYSIS. 303 



(L) PuosriioKK' Acid is present in niuiiurcs as such, ami also as phos- 

 phates of lime, iiuigiiesia, iron, and alumina. 

 Phosphate of lime is most important, and exists in two states, insoluble 

 and solulile. 



Insoluble — Insolu1ile]iliosi)hateoflime,called ) . . , . ^/. o/ 

 rn • 1 • 1 1*1 ( contains about 46 % 



Tncah'u- phosphate, and \ nhosnhoric acid 



Tribasic ].hospluite of lime, ) P^^ospnoriL acid. 



Soluble — Soluljle phosphate of lime, called J contains about Gl % 



Acid phos])hate of lime, ( phosjihoric acid. 



Some analysts prefer to state the soluble ])hosphate as, 



IJiphosjihatc of lime, called also I contains about 72 % 



Monocalcic ])hosphate, ( jdiosphoric acid. 



The soluble phos])hates are usually stated as ecjuivalent 



to so much tricalcic phosphate. 



c 1 , 1 1 1 . ic T 1 1 11 ( 21 ves the equivalent of 



Solnhlc iilios iliatc, multnilied hy ]^>'^ * • i • ^ i i ^ 

 ij- , ,' ' ' ' 1 1 ^ tricalcic phosphate 



Jjlpiloslihati.', ,, „ 1.!; ) 1 -i ^ 



i- i^ ' " " - ^ nearly. 



Phosphate of magnesia occurs in small i[uantity in bones, t^c, and is 



usually reckoned as tricalcic ])iuispliate. 

 Phosphates of iron and alumina when occurring iu !<iii(tii quantity are 

 usually reckoned as tricalcic phosphate. 



X.B. — Phosphates of iron and alumina may occur in such a 

 form as to be v:nrt}tless as a manuie. 

 It would save ambiguity if all phosphates •were described as con- 

 taining so much anhydrous phosjjhoric acid (PoOj) in a 

 soluble or in an insolulile form. 



This amount multijilied by 2-LS would then give the 

 equivalent of tricalcic phosphate. 

 (2.) Nitrogen occurs in manures mostly in three forms. Ammonia salts, 

 nitrates, and albumenoid matter. 



Ammonia sulphate (pure), contains 25j % ammonia. 

 Ammonia chloride (pure), „ 31J „ „ 

 Nitrate of soda (pure), contains 16-47 % nitrogen, equal to 20 % 



ammonia. 

 Albumenoid matter contains about 16 % nitrogen, e(pial to about 

 19 % ammonia, which sooner or later becomes available as 

 plant food. 

 (3.) Potash is found in small amount in most manures, and should be 

 reckoned as anhydrous potash (Kj^)- 

 Sulphate of potash contains potassium = 50 % anhydrous potash. 

 IMuriate oi potash contains potassium = fully 63 % anhydious potash. 



II. FEEDING STUFFS. 



These are chiefly concentrated forms of food ■whose value depends on 



the amounts they contain of albumenoids, oil, and carb ihydrates. 

 Alhumenoids are compounds containing nitrogen, and more or less 

 resemble dry flesh in their composition. They are sometimes 

 called flesh formers. They arc the most valuable constituents of feed- 

 ing stuffs. The percentage of nitrogen contained iu a cake multi- 

 plied by Gj gives the percentage of albumenoids. 



Good linseed, cotton, and rajie cakes should contain from 4 % to 

 5 % nitrogen, about 10 % oil, and about 6 % ash. 

 Carbohydrates are compounds such as sugar, starch, gum, and woodv 

 fibre. (The dirjestiUlity of -woody fibre varies very much, lait 

 chemical analysis cannot determine this with any certainty.) 



All samples to be sent to Dr Andrew P. Aitken, Chemical Laboratory. 



Clyde Street, Edinburyh. 



