The Neglect of Chemistry by Practical Jbarmers. 431 



will easily be enabled to reduce tliem whenever necessary. As a 

 general rule for practical purposes, the amount of chlorine given 

 in the analysis may be doubled, in order to obtain the equivalent 

 of chlorides, subtracting an equal quantity from the soda. 



Phosphoric Acid. — This acid, which appears to exert such a 

 powerful influence on agriculture, is, according to Brande, com- 

 posed of 1 equivalent of phosphorus and 2i of oxygen ; Liebig, 

 while retaining the same proportions, states it as consisting of 2 

 equivalents of phosphorus and 5 of oxygen, or, in other words, as 

 twice the weight. In reducing the phosphates (when necessary) 

 in these tables, I have adhered to the formula of Brande, as being 

 supported by analogy ; for by the adoption of Liebig's formula we 

 should be obliged to consider the neutral phosphates to be con- 

 stituted of 1 atom of acid and 2 atoms of base, whereas, according 

 to Brande, the neutral salt would be composed of 1 equivalent of 

 each. In other words, the salt that is commonly termed a bi or 

 superphosphate, is by Liebig quoted as a neutral phosphate. And 

 this leads me to state, that from the vague manner in which che- 

 mists, in their analyses, class all salts formed by this acid as phos- 

 phates, instead of specifying what particular salt of phosphoric 

 acid is intended, whether subphosphate, neutral phosphate, or 

 superphosphate, it is utterly impossible for any one to determine 

 the exact amount of acid contained in the salt in question. How- 

 ever, in far the greater number of cases, the acid was separated 

 from the base by the analyst himself, but in those that were not 

 so determined, I have always calculated the amount of acid as 

 though the salt was neutral, according to Brande, except when it 

 had a known composition as in bones, 6cc. Liebig certainly asserts 

 that the phosphates in the cereals are bibasic salts (neutral accord- 

 ing to Brande), and in beans and peas tribasic (or, according to 

 Brande, subphosphate) ; but there is not sufficient evidence to 

 show that they always are present in these forms, for in the same 

 sentence in which Liebig states this as a positive fact, he also 

 as positively states that silica and carbonic acid are never found 

 in beans and peas, which fact Professor Way has certainly dis- 

 proved {vide Analyses). This I think will show that even to 

 chemists these tables may be useful, seeing the danger of hazard- 

 ing a decided assertion without sufficient data to verify it. 



Sulphuric Acid. — This acid is composed of 1 equivalent of sul- 

 phur and 3 of oxygen in its dry state (in which state all acids are 

 estimated in all analyses) ; it has a powerful affinity for water. 

 The sulphuric acid, or oil of vitriol of commerce, is combined 

 with 1 equivalent and upwards of water. Its salts are termed sul- 

 phates. As mentioned under the head " Total Sulphur," the 

 amount stated in the column headed "Sulphuric Acid" does not 



