244 Pliillips' Remarks on the 



alkalins. There are first, directions for preparing carbonate of 

 potash from the ashes of wormwood, centaury, and furze ; these 

 are followed by carbonate of potash obtained by the incinera- 

 tion of bitartrate of potash ; from the deflagration of a mixture 

 of bitartrate of potash and nitre ; and from the decomposi- 

 tion of bitartrate of potash by charcoal. We have thus six dif- 

 ferent preparations of carbonate of potash, or, as it is termed, 

 " sous-carbonate de potasse." The only difference in them must 

 of course depend upon a greater or less degree of purity, and 

 therefore the best only ought to be retained and the others ex- 

 punged. It is difficult to discover to what head of imaginary 

 improvements the directions for preparing the carbonate of 

 potash in six different ways belongs. These are followed by 

 " carbonate de potasse" (bicarbonate,) prepared by passing car- 

 bonic acid into a solution of the subcarbonate. 



" Sous-carbonate de Sonde," prepared from barilla and " sous- 

 carbonate d' ammoniaque," by the mutual decomposition of 

 muriate of ammonia and carbonate of lime, follow, next. The 

 proportions directed, are 6 of the ammoniacal salt and 5 of 

 the carbonate ; this last is in too small proportion ; I know 

 both by experiment and Dr. Wollaston's scale, that at least 

 57 parts are required to decompose 60. In the remarks on this 

 preparation it is stated that many are of opinion that lime is 

 sublimed along with the carbonate of ammonia ; a suspicion I 

 never before heard of, and which is certainly groundless. 



Subcarbonate of magnesia is as usual directed to be pre- 

 pared from sulphate of magnesia by carbonate of potash ; but 

 forgetting the accuracy which orders 1000.9 parts of water in 

 preparing snail broth, we are directed to take merely " quantite 

 suffisante" of carbonate of potash, instead of mentioning the 

 quantity required. 



The next head is " alkalis," comprehending " potasse preparee 

 k la chaux et fondue au feu, potasse liquide, sonde caustique 

 liquide, ammoniaque, et magnesie pure." The two first articles 

 require no particular notice, but in preparing soude caustique 

 liquide, that which is before called subcarbonate is here termed 

 carbonate of soda, and as much lime is directed to be used in 



