720 PRELIMINARY OBSERVATIONS, 



CHLOROXALIC ETHER, AND COMPOUNDS DERIVED FROM IT. 



Chloroxalic ether . . C 6 C1 5 O 4 



Chloroxalovinicacid (hydrated) C 6 C1 5 O 4 + C 2 O 3 , HO 



Chloroxamethane . . C 6 C1 5 O 4 + C 2 O 2 , NH 2 



Oxamide .... C 2 O 2 , NH 2 . 



It rarely happens that the crystalline forms of corresponding 1 

 hydrogen and chlorine compounds can be compared, for most 

 frequently the two substances, or at least one of them, does not 

 crystallize, and is altogether incapable of exact measurement. 

 But M. de la Provostaye has succeeded in instituting a com- 

 parison between the crystalline forms of oxamethane and chlo- 

 roxamethane, which he finds to be isomorphous, or rather 

 different secondary forms derived from the same fundamental 

 form.* This would establish the isomorphism of chlorine and 

 hydrogen, but it is to be regretted that so important a conclu- 

 sion should rest upon a single instance, and one also in which, 

 as Mitscherlich remarks, the usual complete identity of form of 

 isomorphous bodies is not observed. 



By exposing pure acetic acid to the action of dry gaseous 

 chlorine, under the direct influence of the solar rays, M. Dumas 

 has replaced the whole hydrogen of that acid by chlorine, or 

 converted acetic acid C 4 H 3 O 3 + HO into chloracetic acid C 4 C1 3 

 O 3 + HO, without altering the capacity of saturation of the acid, 

 or its combining measure in the state of vapour.f Decomposed 

 by alkalies, these two acids give likewise analogous products, 

 acetic acid yielding carbonic acid C 2 O 4 with light carbu- 

 retted hydrogen, C 2 H 4 , and chloracetic acid yielding car- 



TT 



bonic acid C 2 O 4 with chloroform C 2 Q, ; the body last mention- 



3 



ed being viewed as carburetted hydrogen in which three atoms 

 of hydrogen are replaced by three of chlorine. 



Many similar cases of the substitution of chlorine for hydro- 

 gen have been observed, but those already adduced are suffi- 

 cient to illustrate the mode of replacement, and to prove that a 



* Philosophical Magazine, 3rd Series, vol. 18, p. 372. 

 t Annales de Chiraic et de Physique, tome 73, p. 77. 



