50 Notices respecting New Books. 



under other titles the historical development and present position 

 of our modern hypotheses are portrayed with equal fidelity. The 

 wisdom of such a course is sufficiently obvious, and is perfectly in 

 accordance with the rest of the editor's plan. Good theories are 

 now more required than the class of facts with which we are accus- 

 tomed to deal. The law of multiple proportions has, fortunately for 

 numerous investigators, enabled us to correct and employ in logic 

 experimental results of comparatively inferior value ; and it is begin- 

 ning to be felt that with the accumulated labours of the last half 

 century, some of us ought to examine anew the fundamental concep- 

 tions of chemistry. It is quite time to dispute afresh the manifold 

 assumptions of the atomic theory, to discuss the minuter pheno- 

 mena of chemical reactions, to test with rigour the philosophical 

 stability of our definitions and notation. Few among those who, 

 amidst the turmoil of often too hasty experiments, really care to re- 

 flect upon, and to stand face to face with, the full logical conse- 

 quence of their results, will be disposed to doubt that the whole aspect 

 of chemical theory is destined to at least as great a revolution as it 

 has yet witnessed — a revolution in which the gross prevailing mate- 

 rialism will probably have to succumb, when we may expect to 

 enjoy the freedom and purity of exact science. It is, then, most 

 gratifying to find not only that a work like the present, whose au- 

 thoritative influence will not be disputed, contains several special 

 theoretical treatises, but that a great portion of its contents discloses 

 quite as much theoretical as practical discussion. 



Although it formed no part of Mr. Watts's plan (nor indeed 

 would it have been desirable) to record in detail the operations of 

 applied chemistry, there are cases in which he has very properly 

 relaxed a rule whose rigid enforcement might have disappointed 

 some of his readers. Gun-cotton, iron, copper, bleaching, for ex- 

 ample, are subjects which could not be well treated at all without 

 some reference to the manufactory ; and while the student will pro- 

 bably learn from such articles quite as much of processes on the 

 large scale as he desires to know, the manufacturer will find abstracts 

 of and references to all the important memoirs which bear upon the 

 principles he carries out. 



Another point which we must not omit to notice is the fulness 

 with which laboratory operations are described. This is particu- 

 larly the case with the various branches of qualitative and quantita- 

 tive analysis, the description of whose methods has been entrusted 

 to chemists such as Mr. Conington, Drs. Dittmar and Russell, who 

 have made this department their peculiar study. Here and there 

 we have observed an article somewhat too compressed — that on Spe- 

 cific Gravity, for example ; and we have noticed some omissions. 

 We can, however, have no hesitation in attributing such deficiencies 

 to the absolute necessity, beginning to be generally felt, that the 

 whole should be brought to a conclusion as soon as possible ; for it 

 had been found unavoidable to depart from the original plan, which 

 only included three volumes, and also to extend the time of publica- 

 tion. The mature judgment of the editor is nowhere better displayed 



