THE CHEMISTRY OF COOKERY. 779 



away to carbonic acid and water in the case of the pure acid, or will 

 leave carbonate of potash in the case of cream of tartar or other potash 

 salt. 



Unless I am mistaken, this represents violently what occurs gradu- 

 ally and mildly in the human body, which is in a continuous state of 

 slow combustion so long as it is alive. The organic acids of the pot- 

 ash salts suffer slow combustion, give off their excess of carbonic acid 

 and water to be breathed out, evaporated, and ejected, leaving behind 

 their potash, which combines with the otherwise stony lithic-acid tor- 

 mentor just when and where he comes into separate existence by the 

 organic actions which effect the above-described slow combustion. 



If we take potash in combination with a mineral acid, such as the 

 sulphuric, nitric, or hydrochloric, no such decomposition is possible ; 

 the bonds uniting the elements of the mineral acid are too strong to 

 be sundered by the mild chemistry of the living body, and the mineral 

 acid, if separated from its potash base, would be most mischievous, as 

 it precipitates the lithic acid in its worst form. 



For this reason, all free mineral acids are poisons to those who 

 have a lithic-acid diathesis ; they may even create it where it did not 

 previously exist. Hence the iniquity of cheapening the manufacture 

 of lemonade, ginger-beer, etc., by using dilute sulphuric or hydro- 

 chloric acid as a substitute for citric or tartaric acid. I shall presently 

 come to the cookery of wines, and have something to say about the 

 mineral acids used in producing the choicer qualities of some very 

 " dry," high-priced samples that, according to my view of the subject, 

 have caused the operations of lithotomy and lithotrity to be included 

 among the luxuries of the rich. 



It should be understood that, when I recommended the use of bi- 

 carbonate of potass for the solution of casein, all these principles were 

 kept in view, including the objection to the bicarbonate itself. In the 

 case of the cheese the quantity recommended was based on an esti- 

 mate of the quantity of lactic acid existing in the cheese and capable 

 of leaving the casein to go over to the potash. In the case of the peas 

 the quantity is difficult to estimate, owing to its variability. The more 

 correct determination of such quantities is among the objects of fur- 

 ther research, and which I alluded to in my last. 



Speaking generally it is not to the laboratory of the chemist that 

 we should go for our potash salts, but to the laboratory of nature, and 

 more especially to that of the vegetable kingdom. They exist in the 

 green parts of all vegetables. This is illustrated by the manufacture 

 of commercial potash from the ashes of the twigs and leaves of timber- 

 trees. The more succulent the vegetable the greater the quantity of 

 potash it contains, though there are some minor exceptions to this. 

 As I have already stated, we extract and waste a considerable propor- 

 tion of these salts when we boil vegetables and throw away the potage, 

 which our wiser and more thrifty neighbors add to their every-day 



