3S0 Notices respeciing Nt"jc Books. 



duced by galvanic action is similar to solar light : this was proved 

 by its causing the rapid combination of chlorine and hydrogen gases; 

 indeed, Dr. T. afterwards admits that the similarity is confirmed by 

 the chemical effects recently occasioned by phosphorescent or more 

 correctly, incandescent lime. 



The chapters on Electricity and Galvanism do not call for any 

 particular observation : we would merely remark, that the different 

 theories of the pile are given with great brevity and clearness. 



To the subject of galvanism, succeed some remarks on the me- 

 thods of taking specific gravities, and on chemical nomenclature : 

 and then follow affinity and the changes that accompany chemical 

 action ; the subject of crystallization is dispatched with most un- 

 usual brevity, the primary forms of crystals are not even mention- 

 ed ; indeed we suspect both from this circumstance and some of tire 

 author's subsequent statements respecting crystalline forms, that 

 they have received but little of his attention. 



In treating of Cohesion, Dr. Turner offers some observations, to 

 the accuracy of which we can by no means assent. Thus muriate of 

 lime is stated to be decomposed by carbonate of ammonia, in con- 

 sequence of the insolubility of the carbonate of lime. Now as in- 

 solubility is a property arising from combination, it cannot be the 

 cause of it : it is unquestionably true that insolubility may, and cer- 

 tainly does in many instances, prevent chemical action ; but it ap- 

 pears to us to be utterly confounding cause and effect, to imagine 

 that a property which a body would possess when formed, can be the 

 cause of its production : supposing also that insolubility were the 

 cause which produced the carbonate of lime, it ought also to pre- 

 vent its decomposition by muriatic acid, and the carbonates of lead, 

 lime, and barytes ought to be as insoluble ia any acid as their re- 

 spective sulphates. 



We cannot agree with Dr. Turner, that if four substances be 

 mixed together, the compound which is insoluble will, in all cases, 

 be formed ; the fact that prussian blue and peroxide of mercury, 

 both substances insoluble in water, yield by boiling in it a soluble 

 cyanuret of mercury, is a sufficient refutation of this statement as 

 a general law. 



Again ; the author observes that some substances are decora- 

 posed on account of their volatility : this argument is similar to that 

 respecting the insolubility, and is refuted by the same reasoning; 

 viz. that causes cannot act previously to their existence : if the 

 volatility of a body in its uncombined state, were to influence it 

 while in combination, hydrate of potash ought to be as easily de- 

 composed as hydrate of copper ; and indeed the existence of hy- 

 drate of potasli at a red heat completely disproves another of Dr. 

 Turner's statements, viz. that all compounds which contain a vola- 

 tile and a fixed principle, are liable to be decomposed at a high tem- 

 perature. 



The most remarkable exception to the accuracy of this state- 

 ment is the compound of chloride of phosphorus and ammonia, dis- 

 covered by Davy ; this substance, composed of three elementary 



gases, 



