334 Analysis of Scientific Books. 



All our respectable British compilers seem now fully possessed 

 with this idea. But M. Theeand, in his third edition (1821,) of his 

 excellent Traite, has neglected this principle of arrangement alto- 

 gether, and has consequently created a strange jumble among the 

 elementary substances. He begins, for instance, with oxygen, and 

 under this head discusses the theory of combustion and of flame, 

 as if these phenomena possessed that indispensable connexion with 

 oxygen, which was the leading article of the Lavoisierian creed. 

 His next great division comprehends the simple combustibles, non- 

 metallic, which are distributed in the following order ; hydrogen, 

 boron, carbon, phosphorus, sulphur, selenium, chlorine, iodine, and 

 azote. Thus many of the most beautiful chemical analogies are 

 violated, to the no small perplexity of the student. 



Dr. Henry has at length in this edition adopted as the basis of 

 his arrangement, that originally given in Sir H. Davy's Elements, 

 and followed up and extended in Mr. Brande's Manual. In the 

 sequel of the introduction (which is the introductory lecture long 

 ago delivered in Manchester, and reprinted in the former edi- 

 tions,) he has given a few paragraphs descriptive of the arrange- 

 ment of the work. 



The first chapter entitled " Of a chemical laboratory and appa- 

 ratus," is chiefly a reprint from the former editions. Some formulae 

 are now added by Mr. Dalton, for equating the volumes and spe- 

 cific gravities of moist gases. Mr. Dalton assumes 0.620 as the 

 specific gravity of aqueous vapour in air at 60° F, and not 0.472 

 as Drs. Apjohn and Thomson would have it. (See Annals of 

 Philosophy, May, 1822.) " The specific gravity," says Mr. Dalton, 

 "of pure steam compared with that of common air, under like 

 circumstances of temperature and pressure, is according to Gay- 

 Lussac as 0.620 to 1.0." 



But as each species of gaseous matter has its volume equally 

 affected by change of temperature, the relation 0.620 to 1, will 

 continue to be equally just at the temperature of 60° F, as at that 

 of 212°, at which point M. Gay-Lussac's experiments were made. 

 Hence we perceive the fallacy of Dr. Thomson's and Dr. Apjohn's 

 determinations in the Annals of Philosophy for April and May, 

 1822. A more popular view of this important practical subject 

 should have been given in an elementary work. To a large propor- 

 tion of chemical students, Mr. Dalton's exposition will be unin- 

 telligible. A table might have been given for reducing the volume 

 of moist air, to that of dry, between the ordinary range of experi- 

 menting on gases, viz., from 50° to 70° Fahr. 



The second chapter is entitled Chemical Affinity ; under which 

 head we scarcely expected to find cohesion and crystallization. 

 Here the principles of corpuscular philosophy are inculcated ; but 

 we cannot compliment our author, either on the soundness or pro- 

 fundity of his views. His primary enunciation is incorrect. " All 



