384i Notices respecting New Books. 



of water. Here the oxigen of the water unites with the zinc, and 

 the hydrogen is set free ; the oxid then combines with the sulphuric 

 acid, to form the sulphate. The hydrogen obtained by this process, 

 is much purer than that got by iron. It has less unpleasant odour, 

 and it is of less specific gravity. By evaporating the solution in the 

 retort, crystals are obtained. This is the mode by which the purest 

 white vitriol is prepared ; but that of commerce is generally procured 

 by a process similar to that by which green and blue vitriol are formed, 

 by exposing the ore of zinc and sulphur to air and moisture, by 

 which both combine with oxigen to form sulphuric acid and oxid, 

 "which unite, and form the sulphate." 



In the first place the hydrogen is not quite pure, for it is not 

 free from smell ; and at p. 108. Dr. Fyfe allows that the smell of hy- 

 drogen is derived from its impurity. Indeed the hydrogen though at 

 first stated to be pure, is afterwards mentioned to be so only compara- 

 tively. The oxygen of the water is properly represented as combining 

 with the zinc ; but the hydrogen is not so clearly stated to be derived 

 from the decomposition of the water, nor that when it is set free it is in 

 the gaseous form. That hydrogen " is got by iron" may be a Scotticism ; 

 but it is neither an English nor a chemical expression ; the metal not 

 possessing, as far as we know, any such power as that here attributed 

 to it. We may certainly obtain crystals of sulphate of zinc by evapo- 

 rating the solution in the retort; but we think most persons would 

 prefer to transfer it to a basin either of glass or porcelain. The 

 ore of zinc and sulphur is an incorrect expression for sulphuret of 

 zinc; it is an ore of zinc, but not of sulphur. Indeed we never heard 

 of an ore of the last mentioned substance, nor do both combine with 

 the oxvgen to form sulphuric acid and oxide ; the former only be- 

 comes an acid ; the latter only an oxide. 



In a future edition we would strongly recommend Dr. Fyfe to give 

 more precise directions for performing processes, and to state the 

 composition of bodies more in detail. 



The second work, as announced by the title, contains directions for 

 performing various chemical experiments ; and it is the production, 

 savs the advertisement, of "one allowed to be a successful experi- 

 mentalist." We have not minutely examined the details ; but as far 

 as we have proceeded, the experiments are collected from chemical 

 authors well known to the public. We do not however question the 

 assertion that some are original. 



On the subject of Definite Proportions the author (Mr. John Muu- 

 ray if we mistake not) has committed one of the most glaring faults 

 we ever remember to have seen in print. He has actually, twice 

 stated that Dr. Thomson assumes the numerical representation of 

 oxygen gas to be 1. 11 1 1 , instead of 1 ; thus mistaking and misstating 

 the specific gravity of the gas in question for its atomic weight. 

 As the natural consequences of these blunders, he has also given the 

 atomic weights of hydrogen, chlorine, muriatic acid and water, all 

 erroneously. 



LXIII. Pro- 



