Notices respecting New Books. 099 



author's theory of definite proportion in the combination 

 or decomposition of bodies becomes easily comprehended. 

 ** All bodies that differ in their nature, combine with dif- 

 ferent degrees of force." This is exemplified in the tanning 

 substance being attracted from water by skins ; in indigo 

 and other dyes being attracted by vegetable and animal fibres, 

 and new combinations of them effected. In consequence 

 of this principle, one body is capable of separating others 

 from certain of their combinations : from the same circum- 

 stances, mutual decompositions of different compiumds take 

 -place. Hence double affinity, or complex chemical attrac- 

 tion. This leads us to the author's principles of uefinitb 



PROPORTIONS. 



'^ 7- If one part of pure oxygen gas, and two parts of pure 

 hydrogen gas, in volume, be mixed together in a glass tube, 

 over mercury, furnished with wires for passing the electrical 

 .spark through it, and they be inflamed by the electrical 

 spark, the gaseous matter will disappear, and water will re- 

 sult. If two parts of oxygen be employed, and two of hy- 

 drogen, one part of oxvgen will reinain : in whatever pro- 

 portions they are mixed together, it is found, that one of 

 oxygen always condenses two of hydroeen. It is evident, 

 then, that oxygen and hydrogen combine only in definite 

 proportions, and that the water resulting is always the same 

 in it? constitution. 



" If a piece of well-burnt charcoal be introduced into a 

 vessel, two-thirds filled with oxvgen gas, overmercurv ; and 

 the mercury be brought to the same level on the inside and 

 on the outside of the jar, and the charcoal be inflamed by 

 a burning glass, there will be at first an expansion; but 

 after the experiment is over, it will be found that the vo- 

 lume of the gas has not perceptibly altered ; and if the char- 

 poal has been in sufficient quantitv, the whole of the oxygen 

 will be found converted into carl)onlc acid : now the den- 

 sities of oxygen gas, atid carbonic acid gas, in whatever way 

 they are formed, are always the saine; and to each other as 

 34 to 47 nearly. It is evident, then, that carbonic acid 

 must always contain the same weight of oxye,en and char- 

 coal. Jf there is twice as much oxygen in the vessel as is 

 necessary for the consumption of the charcoal, half of it re- 

 mains untouched: and if the charcoal is jiartly unconsumed, 

 still the gas is the same in quality ; it always contains by 

 weight 5*7 of charcoal and 15 of oxygen. 



There is an inflammable gas, called carbonic oxide, which 

 burns with a blue flame, and which is obtained by igniting 

 together zinc filings and chalk. When two in volume of 



this 



