Notices respecting Ncio Books. 381 



gases, and a very volatile solid, is not only difficult of decomposi- 

 tion, but is not volatilized at a red heat ; many similar examples 

 might be quoted. 



In refuting an error respecting the action of quantity in modify- 

 ing affinity (p. Hi), it appears to us that the author has not been 

 fortunate in the selection of his example : — Thus he states, that 

 " acids and alkalies have a tendency to unite in more than one pro- 

 portion, and will readily form salts with excess of acid or of base 

 when circumstances are favourable to their production." If by this 

 it is meant that the alkalies form compounds with acids which con- 

 tain less than one atom of acid, we do not remember any such case ; 

 but we readily admit the formation of salts with excess of acid: and 

 this, according to Dr. Turner, " explains why nitrate of potash can- 

 not be entirely decomposed by a quantity of sulphuric acid ; which 

 is just sufficient for neutralizing the alkali : the sulphuric acid," he 

 continues, " instead of taking the whole of the potash, unites with 

 a part of it and forms the bisulphate. This tendency to the forma- 

 tion of an acid salt accounts for the fact quite satisfactorily ; nor is 

 there any reason to infer the co-opei'ation of any other cause." 

 We are enabled by the results of direct experiment to show the 

 inaccuracy of these statements. When 100 parts of nitre were de- 

 composed by the equivalent quantity of sulphuric acid, more than 

 -^^ of the whole quantity of nitric acid were procured, and the salt 

 left in the retort weighed 86-2 parts, which is the precise atomic 

 quantity of sulphate of potash obtainable by decomposing the nitrate 

 by its equivalent of sulphuric acid : that it contained no bisulphate 

 of potash, was proved by its being rendered alkaline by ^'^ of its 

 weiglit of carbonate of potash : it is scarcely necessary to add, that 

 if two atoms of sulphuric acid were required to decompose one 

 atom of nitrate of potash, only -,lflj of the whole quantity of nitric 

 acid could have been procured, instead of -^y^j ; the loss of 8 parts 

 being inevitable in the operation. When treating of nitric acid, we 

 shall briefly resume the subject of employing two atoiiis of sulphu- 

 ric acid to decompose one atom of nitre. 



We have already alluded to Dr. Turner's " Introduction to the 

 Study and Laws of Chemical Combination ;" this work the author 

 has judiciously introduced, with a few alterations, into the present 

 volume. A clear and excellent view is given of the subject; but 

 we shall notice two or three important errors, — mere slips of the 

 pen, — two of which also occur in the original treatise. First, in 

 p. 13,3, we have 05554, instead of 0-5554 ; and 9720, for 0-9720 : and 

 in page 148, the ratio of the oxygen of the acid and of tiie base in 

 neutral sulphates, is stated to be as one to three, instead of three 

 to one. 



The third section commences with an account of the properties 

 of Oxygen ; and upon some of the statements which it contains, we 

 shall offer a few observations. Dr. Turner has correctly stated the 

 sources from which oxygen is procurable: he might, however, have 

 added deutoxide of lead to the list. He agrees with Dr. Thomson 

 in stating, tiuit 44 parts = 1 atom of peroxide of manganese, lose 

 4 parts of oxygen by exposure to a red heat and become deutoxide. 



Dr 



