194, 195] Analysis and Valuation of Manures 121 



through a full course of analytical chemistry to do all the work 

 which is ordinarily necessary in an agricultural laboratory. 



ANALYSIS OF MINERAL PHOSPHATES 



194. Moisture. — The moisture given off at ioo° C. is 

 very small and of no importance, and it is usual to estimate it 

 together with the combined water and organic matter. If, 

 however, it should be required, it may be found by weighing 

 out about 2 grams of the sample in a porcelain capsule, and 

 heating in the steam oven until it ceases to lose weight. The 

 loss is the moisture. 



195. Combined Water and Organic Matter.— The 

 portion used for the estimation of moisture is emptied into a 

 weighed platinum dish, heated over an Argand at the highest 

 temperature procurable without allowing the flame to touch 

 the platinum. After about an hour the dish is placed in a 

 Fletcher muffle furnace (see fig. 17), and kept at a bright 

 yellow heat for twenty minutes. At the end of this time the 

 gas is turned off, and the open muffle allowed to cool to a dull 

 red. The dish is then removed to a desiccator and, when 

 cool, weighed. The loss of weight gives the sum of the com- 

 bined water, the organic matter, and the carbonic anhydride. 



If in the subsequent analysis it should be noticed that the 

 mineral effervesces on the addition of hydrochloric acid, the 

 C0 2 may be estimated by one of the methods described in 

 paragraphs 48-56. The amount of C0 2 is, however, not of 

 much consequence to the manure manufacturer (see page 155), 

 and very often a fairly accurate idea of it may be obtained from 

 the quantities of lime and phosphoric acid present, the excess 

 of lime over the phosphoric acid being considered as CaC0 3 . 

 This method of calculation is of course impossible in the case 

 of apatites. 



