Analysis of Scientific Booka. 405 



dered in many instances necessary by the magnitude and extent 

 of their operations. 



But to proceed with our author's book : — The third section 

 treats " on the presence of prussic acid in animal, vegetable, 

 and mineral substances." We are told at its outset, ** that 

 although the blood contains the principles of the prussic acid, 

 it is not there found ready formed, since they require the pre- 

 sence of an alcali to influence that peculiar attraction and com- 

 bination of their molecules which constitutes the acid in ques- 

 tion.'* This, and the two following paragraphs, one of them 

 purporting to be an extract of the author's notes taken at Vau- 

 quelin's lectures, are to us quite unintelligible : there is alcali 

 enough in the blood, if alcali only were wanted to influence 

 " that peculiar attraction and combination of molecules," as 

 the Doctor learnedly expresses it, which constitutes prussic acid. 

 This part of the work is especially bare, and betrays a " poverty 

 in the land," which we had little expected. The formation of 

 prussic acid by the combustion of animal matter, is a very curi- 

 ous but difficult branch of chemical inquiry, upon which we had 

 hoped to have gained some information from Dr. Granville's 

 book ; he either should not have meddled with it, or given a 

 clear epitome of what is known upon the subject. 



The formation of prussic acid in certain diseases, its presence 

 in vegetable products, and its supposed existence in the mineral 

 kingdom, are next superficially adverted to ; in relation to the 

 latter subject, " we may instance," says Dr. G., ** as the only 

 mineral substance which has been found to contain prussic 

 acid, thefer azure of Haiiy." Whereas Haiiy himself {Traite de 

 Minhalogie^ IV., 121,) speaking of the term Native Prussian 

 Blue applied to that substance, says, " Cette denomination ne 

 parott ^tre fondee sur aucune experience decisive ;" and, more- 

 over, we have the joint authority of Klaproth, Fourcroy, and 

 Proust, for regarding the fer azurg of Haiiy as a phosphate of 

 iron. The Doctor's suggestion of the existence of Prussian blue 

 in lapis lazuli, is equally improbable. The colour of lapis lazuli 

 is not injured by a low red-heat, and it is used by the painter 

 under the name of ultramarine, as a most permanent colour ; 



