22 G ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



ter-bath for twenty-four hours, with fifty times its weight of 

 water, much of it is transformed into a soluble gum, which 

 no longer swells after drying: this new substance is pectin ; 

 (3) that under the action of water containing one per cent, 

 of acid, the production of pectin takes place in two or three 

 hours. It becomes entirely soluble, and alcohol precipitates 

 pectin, not arabin, from the solution. Alkalies change it into 

 pectates and meta-pectates. Hence gum tragacanth consists 

 for the most part of a pectic principle insoluble in water, ap- 

 parently identical with Fremy's pectose. From it by precip- 

 itating the pectin solution by barium hydrate and decom- 

 posing by an acid, pure pectic acid was obtained. Upon 

 analysis, gum tragacanth yields as follows : Water, 20 per 

 cent.; pectic compounds, 60 per cent.; soluble gum, 8 to 10 

 per cent.; cellulose, 3 per cent.; starch, 2 to 3 per cent.; min- 

 eral matter, 3 per cent. ; nitrogenous matters, traces. 4 B, 

 III., v., 361, April, 1875. 



CAEBONYLES, A NEW CLASS OF ORGANIC BODIES. 



Berthelot has recently instituted a new class of organic 

 bodies, to which he has given the name Carbonyles, and to 

 which he assigns three bodies hitherto rather ambiguous in 

 their chemical behavior. These are allylene oxide, dipheny- 

 lene acetone, and ordinary camphor, to which he gives the 

 new names dimethylene carbon yle, diphenylene carbonyle, 

 and terebutylene carbonyle. The distinguishing feature of 

 carbonyles is their double function. In the first place they 

 act like aldehydes, being able to fix hydrogen directly and 

 to produce alcohols; while they are themselves reproduced, 

 like aldehydes, by hydrogenization of these alcohols. Again, 

 like aldehydes, they may be formed by the direct or indirect 

 oxidation of hydrocarbons; camphene hydride and oxygen 

 producing camphor precisely as ethylene hydride and oxygen 

 produces common aldehyde. But, secondly, it is to be ob- 

 served that while aldehydes are produced by the indirect 

 oxidation of saturated hydrocarbons, carbonyles result from 

 the indirect oxidation of unsaturated hydrocarbons. This is 

 a very material difference, since, besides its aldehydic func- 

 tion, the carbonyle molecule is itself unsaturated for this 

 very reason, and hence can combine directly with other 

 saturated molecules. Like the radical carbonyl itself, from 



