Notices respecting NeMo Books. 383 



of sulphuric acid for decomposing 1 atom of nitre, is stated by 

 Dr. Turner to be the facihty which it affords of removing the resi- 

 dual salt from the retort ;— this we will admit : he continues, how. 

 ever ; " but though it is advisable to use more than 1 atom of 

 sulphuric acid, it is important to employ no more than is really re- 

 quired for decomposing the nitre with advantage. An unnecessary 

 excess," he continues, " is not only unceconomical, but positively 

 hurtful ; for some of it is then apt to pass off in vapour during the 

 distillation, and thus render the nitric acid impure. The propor- 

 tions of the Edinburgh College are calculated to fulfil all those 

 conditions ; the excess of sulphuric acid is suflRcient to decompose 

 almost all, if not the whole of the nitre, and a pure nitric acid is ob- 

 tained." 



Now it appears to us that some of these statements are at variance 

 with others ; the proportions employed by the Edinburgh College, 

 are two parts of sulphuric acid and three of nitre : if then, according 

 to Dr. T.'s statement, " nitre cannot be wholly decomposed by a 

 quantity of sulphuric acid, which is merely sufficient for forming a 

 neutral sulphate," the proportions of the Edinburgh College do not 

 and cannot " fulfil all the conditions" alluded to, nor is the " excess 

 of sulphuric acid sufficient to decompose almost all the nitre ;" and 

 the residue of the Edinburgh process, instead of being "a mixture 

 of the sulphate and bisulphate of potassa," as Dr.Turner states, must, 

 according to his own showing, be a compound of about 128 parts of 

 bisulphate of potash and 45 of nitre. It may also be observed that when 

 2 atoms of sulphuric acid are employed, no portion of it ever rises 

 and contaminates the nitric acid ; nor indeed can it do so, consist- 

 ently with the opinion that it is necessary to combine with the pot- 

 ash of the nitre. 



As far as we have observed, there are a few, and only a few 

 statements which require notice, in looking through a large 

 further portion of Dr. Turner's work. We would, however, inquire 

 whether it would not be a more correct expression to speak of 

 evolving than of forming hydrogen and other elementary gases; 

 & mixture of nitric oxide and hydrogen gas burns with a greenish 

 and not with a white flame (p. 187). It may also be difficult to con- 

 ceive how an orange-coloured liquid, like nitrous acid, should give 

 different shades of green and blue merely by being diluted, and yet 

 green muriate of cobalt becomes red by dilution, and green muriate 

 of copper blue by the same means. We do not by these observations 

 mean to deny the probability of Dr. Turner's suggestions, at p. 193, 

 respecting tlie nature of the changes produced in nitrous acid by 

 mere dilution ; all we intend is to show that the case is not without 

 a parallel. We do not know that it is of much consequence that the 

 same nomenclature should in all cases be adopted ; but on a subject 

 which is always puzzling to learners, — we mean the atomic theory, 



it rather increases the difficulty to use numerous terms in the same 



sense, especially when treating of any peculiar substance. In p. 210, 

 Dr. Turner states that carbonic oxide is regarded as a combination 

 of ono proportion of carbon = (5 and one of oxygen = 8; and car- 

 bonic acid of one atom of carbon = 6 and two of oxygen = 16. 



The 



