D. CHEMISTRY AND METALLURGY. 75 



A NEW CINCHONA ALKALOID. 



A new alkaloid has, it is said, been detected in the mother 

 liquor obtained in the manufacture of sulphate of quinine, 

 distinguishable from the cinchona alkaloids by the solubility 

 of its salts, which renders it very difficult of separation from 

 the uncrystallizable quinoidin. It has not yet been deter- 

 mined whether it is contained in all the species of cinchona, 

 or, if not, in which of them ; nor have its physiological prop- 

 erties been experimented upon. 16 A,July^ 1871, 405. 



REMOVAL OF ODOR FROM TANNIN. 



It is said that the peculiar odor of commercial tannin may 

 be entirely removed, and thus better fitted for officinal ad- 

 ministration, by first dissolving six parts in twelve parts of 

 warm water, placed in a porcelain vessel, then pouring the 

 solution into a flask after adding from one half to one part 

 of ether, and shaking it up thoroughly. The mixture at first 

 appears of a dirty green and very turbid, but settles in a few 

 hours, the coloring matter sinking to th*e bottom in the form 

 of a flocculent coagulum. The liquor is then to be filtered, 

 and the filtrate evaporated. Tannin thus prepared has no 

 odor, and gives a perfectly clear solution with water. Ding. 

 Poly.Joum., CXCVIL, 1., 98. 



COMBUSTION OF SMOKE. 



It is generally understood that the cause of smoke, in the 

 case of burning wood and other forms of carbon, is due essen- 

 tially to an insufficient supply of air, which prevents the 

 combustion from being complete. This may seem strange 

 when we are assured that the gases produced by combustion, 

 of coal especially, contain an excess of air. This apparent 

 inconsistency, however, is explained when we are informed 

 that by a deficiency of air is simply meant that this is the 

 case in each volume or stratum of air in which combustion 

 has taken place ; but the gases which pass into the chimney 

 may be regarded as a collection of such volumes or strata 

 mixed with others rich in oxygen, and these, in most instan- 

 ces, being too little heated to admit of their enterino; into 

 combination. 



From these theoretical considerations, it follows that, for 



