14C Jna/^sis of Scientijic Books. 



algebraist ; excellent computer ! we are apt to think, that, 



(0.66 y. 0.0694) + 0.9722 



X : 0.61 1 



1.66 



precisely as we gave above, for both rules are identical. The 

 Doctor, we are told, has hired an ingenious mechanic, for a abort 

 time, to make experiments for him ; let him next hire an arith- 

 metician to compute their results, and a person, versant in 

 English composition, to clothe them in words ; and he may then, 

 probably, publish a better system of chemistry. But the most 

 amusing detection remains. On turning our eyes to the Doctor's 

 paper, so often appealed to by himself, in the Wernerian Memoirs, 

 we find, page 507, the following statement about his true car- 

 buretted hydrogen : " after depriving it of its carbonic acid, I 

 found its specific gravity 0.611, that of air being 1.000." What 

 a marvellous coincidence ! absolutely the same specific gravity 

 by experiment, as the above theoretic mixture of olefiant gas and 

 hydrogen, which possesses the chemical properties of his carbu- 

 retted hydrogen ! Doctor Thomson is here caught in his own trap. 

 To be sure he will try to get c^pt of it by saying, as he does in the 

 Wernerian Memoirs, that the ditch gas contained 12,5 per cent. 

 of air; but as he gives us no experimental evidence for that 

 assumption, we beg leave to withhold our assent. This 12.5 

 per cent, is necessary for his atomic hypothesis of the density 

 of the gas, but we find no proof or. probability of its presence. 

 When we figure to ourselves, the Doctor poking the black 

 slime at " Restalrig" for fetid gas, and wishing us to believe, 

 that he caught in his funnel of " greasy paper," 12i per cent. 

 of pure atmospheric air, from putrid mud, we must say, 

 " Credat JudcEus Apella," hand nos. We see that the experi- 

 mental density corresponds minutely with that deduced from cal- 

 culation. The reason that the specific gravity of this gaseous 

 mixture, was so accurately obtained by him, is its having the 

 same density nearly as aqueous vapour. Hence moisture intro- 

 duced no error into the result, as it has done in his specific 

 gravities of the denser gases, of which there is so pompous an 

 account in his September and October annals. The atomic 

 theory shews us, that if two atoms of carbon act chemically on 

 two atoms of water, there ought to result, one atom of carbonic 

 acid(=l carbon + 2 oxygen) -f- 1 atomof olefiant gas (:= 1 carbon 

 -|- 1 hydrogen) -|- 1 atom of hydrogen. Of the latter gas, which 

 is so very light, a small proportion escapes, leaving the mixture 

 of 1 volume of olefiant + |- of a volume of hydrogen. We lay 

 little stress on tliis atomic representation of the process, but 

 merely throw it out to accommodate Dr. Thomson, in return for, 

 the numerous iynesfatui, of a similar kind, that he has conjured 

 up before us. 



Boron and silicon occiipy the third and fourth sections.. They 



