452 Analyses of Books. [Junk, 



obtained by the first part of the process which they direct, 

 should be redistilled with an additional quantity of nitre. The 

 acid is as pure as possible, and has the solvent power and 

 specific gravity which they attribute to the rectified acid ; and 

 by omitting the redistillation, time, trouble, expense, waste, and 

 a disagreeable operation, are avoided, without losing even the 

 shadow of an advantage. 



The directions for preparing liquor ammonia?, as far as the 

 proportions of the ingredients are concerned, remain unchanged, 

 and so also does the quantity of the fluid to be distilled from 

 them: but it is now directed that the temperature of the re- 

 ceiver should not exceed 50 degrees. Now one of two things 

 must happen ; the strength of the product is either increased 

 by this alteration, or it is not. If it be unattended with ad- 

 vantage, the only remark required is obvious : — why make the 

 alteration? If, on the other hand, the strength of the solution 

 is increased as one might expect, why is its specific gravity, 

 and consequently its strength, stated to be similar to what it 

 was in the last Pharmacopoeia 1 The specific gravity was there 

 fixed at 0*960, aud it remains the same, although we are now 

 directed to keep the receiver cooled to 50° for the obvious 

 purpose of rendering it more powerful. 



The method of preparing potassse acetasis altered, but I much 

 question whether any improvement has been introduced, except 

 that of using pure acetic acid instead of distilled vinegar ; 

 by this the inconveniences arising from the mucilage which the 

 latter contained will certainly be obviated, and I have no doubt 

 but a pure and white salt is at once procurable. In the late 

 Pharmacopoeia, the directions were to boil the solution of ace- 

 tate of potash to dryness, but now the solution is to be evapo- 

 rated until a pellicle forms, and this being removed is to be 

 preserved and dried, as acetate of potash. I have not tried this 

 process, but if practicable, it must, I think, be tedious, and 

 unattended with any advantage over the method of evaporation 

 to dryness. 



The next alteration which I shall notice is an unquestionable 

 improvement — that of procuring carbonic acid from the decom- 

 position of carbonate of lime for the purpose of preparing car- 

 bonate or rather bicarbonate of potash, instead of obtaining it 

 as in the last Pharmacopoeia, (and even then in too small quan- 

 tity,) from the decomposition of subcarbonate, or rather sesqui- 

 carbonate of ammonia. But here my commendation must end ; 

 for by a very obvious oversight, the College have directed the 

 solution of carbonate (bicarbonate) of potash, to be evaporated 

 for the formation of crystals, when there is not actually more 

 than about one-fifth of the water present necessary for their 

 solution. Indeed on account of the very strong solution of the 

 subcarbonate (carbonate) of potash which the College direct fur 

 conversion into bicarbonate, I have but little doubt that the 



