2824.] Pharmacopoeia Londhiemis. 451 



and I think the College might advantageously have omitted the 

 latter, using the former in all cases instead of it. Added to 

 which acetic acid is scarcely a proper appellation for an acid 

 containing so much mucilage, that acetates are with diffi- 

 culty formed by using it. 



In the last Pharmacopoeia directions were introduced for the 

 preparation of citric acid ; these are still continued, although 

 the acid is now also introduced into the materia medica ; in 

 the present Pharmacopoeia, a formula is also given for preparing 

 tartaric acid, but by what I presume to be an oversight this acid 

 is not included in the Materia Medica, as it ought to have been 

 for the same reasons that induced the placing of citric acid under 

 that head. With respect to the tartaric acid, it may also be ob- 

 served, that one-half of that which the bitartrate of potash con- 

 tains is lost. The method directed is to saturate the excess of acid 

 in the bitartrate by causing it to decompose carbonate of lime, and 

 then the tartrate of lime formed is to be treated with sulphuric 

 acid. As far as it goes this is well, but no notice whatever is 

 taken of the remaining tartrate of potash, which the College 

 should have directed either to be crystallized ; or to be decom- 

 posed in the well-known manner by muriate of lime, this being a 

 refuse product of more than one pharmaceutic preparation. 

 With regard to benzoic acid, the College have adopted an 

 improvement by restoring the process by sublimation, which 

 they rejected from the Pharmacopoeia in 1809. But the medi- 

 cine is too unimportant to require any particular notice. In 

 preparing muriatic acid, the College direct, as before, that its 

 specific gravity should be 1-160; but they have now given the 

 saturating power of crystallized carbonate of soda as a measure of 

 its strength, instead of that of carbonate of lime, as formerly. I 

 found that the acid procured by the College process had a speci- 

 fic gravity of P1645, and as 100 parts of it decomposed almost 

 exactly 44 of carbonate of lime, they would saturate the equiva- 

 lent quantity of crystallized carbonate of soda, or 134 parts. 

 The College say 124, and this, therefore, is probably almost 

 correct with respect to acid of specific gravity 1*1 (30 as directed. 



No alteration has been made in the process for preparing 

 nitric acid ; but with regard to the standard for ascertaining its 

 saturating power, that, as in the case of muriatic acid, is changed 

 from carbonate of lime to subcarbonate of soda; and although it 

 is stated with great precision that 100 grains saturate 212 of crys- 

 tallized subcarbonate of soda, (the quantity by calculation being 

 only half a grain more,) I am yet of opinion that the method of 

 using carbonate of lime is the best, for reasons which Dr. YVollas- 

 ton has stated ; the fact, however, is, that neither plan is at all 

 needful when the specific gravity is stated. With, however, the 

 near approach to accuracy which the College have now made, 

 there can be no objection to the statement. I cannot con- 

 ceive why the College persist in ordering that the nitric acid 



2o2 



