Gurney on Chemical Science. 305 



In this same lecture we learn, at the bottom of p. 154, that it is 

 impossible to make a room air-tight, and that health is injured in 

 exact proportion as we do it; but a few lines further on we are 

 told, that if the room be heated by flues, it may safely be made 

 air-tight ! 



At pages 156 and 157, there are some sharp remarks upon Sir II. 

 Davy's experiments respecting the temperature of flame, which 

 according to Mr. Gurney, involve much contradictory evidence. 

 Now as we have unfortunately not profited by Mr. Gurney's tui- 

 tion, but happen to have received part of our chemical education 

 under the former master ; and as we belong to a school, one ob- 

 ject of which is to teach his doctrines, and set forth his discoveries, 

 we cannot be supposed to come unprejudiced to the consideration 

 of our author's views, and therefore leave the determination of this 

 subject to less biassed judges, observing at the same time, that we 

 have looked in vain for those interesting discoveries which Mr. G. 

 tells us he has made (p. 103) relating to gaseous bodies. 



Thus far we have exposed our author's methods of handling the 

 higher departments of chemistry; we now descend to the more 

 immediate drudgery of the laboratory. 



At p. 180, Mr. Gurney attributes to the " zipper sides" of the 

 leaves of plants, those functions which chiefly belong to their lower, 

 and generally unvarnished, surfaces; and at p. 184, we find that 

 " metallic oxides are generally reduced by the aid of fluxes, one of 

 which is carbon," which in our conception of the term is no flux 

 at all. 



Speaking of the composition of water, it is stated to consist of 

 85 oxygen, 15 hydrogen; the proper numbers are 89 and 11. 

 Nitrous oxide is said to contain 1 nitrogen and 2 oxygen by 

 volume — those numbers should be reversed ; and it is incautiously 

 asserted that this gas may be breathed not only without injury, 

 but often with benefit, for Mr. Southey, the Poet Laureate, declared 

 that the sensations he experienced, were perfectly new and de- 

 lightful ! 



In the 9th lecture we are informed that " it is likely that the 

 Aurora Borealis consists of hydrogen gas, sustained at a certain 

 elevation in the air, in virtue of its lightness, and ignited from time 

 to time by electricity. The ignis fatuus also consists chiefly of 

 hydrogen, in combination with phosphorus, generated by the de- 

 composition of vegetable matter, and lighted by the heat given 

 out during the act of decomposition," all which to our obtuse un- 

 derstandings, appears very unlikely, though the reasoning if not 

 brilliant is at least luminous. 



A little further on we are told, that the air emitted from the 

 lungs consists of nitrogen and carbonic acid, and that as soon as 

 it escapes from the mouth, the nitrogen ascends, and the carbonic 

 acid descends, " thus preventing all danger of our again taking in 



Vol. XVI. X 



