248 Scientific Intelligence. 



SCIENTIFIC INTELLIGENCE. 



I. Chemistry and Physics. • 



1. On the Stalagmometer and its tise in quantitative analysis. — 

 Two years or more ago, Traube observed the markedly greater 

 effect of iso-amyl alcohol, in lowering the height of a capillary 

 column, over that of ethyl alcohol, even when both were diluted 

 with water to the same extent. He based upon this observation 

 a method for estimating the amount of fusel oil in alcoholic liq- 

 uors, and constructed an instrument, called a capillarimeter, by 

 which the capillary elevation could be easily measured. In a 

 liquid containing twenty per cent of alcohol, one-tenth of a per 

 cent of fusel oil would lower the column a millimeter. As this 

 instrument did not prove convenient in practice, the author 

 adopted a modified method of testing, also founded on the princi- 

 ple of surface tension, consisting simply in counting the number 

 of drops contained in a given volume of the liquid. To facilitate 

 the process, a bulb tube was used, having marks above and below 

 the bulb, the volume between the two marks being known. Be- 

 low, the tube was bent at right angles, united to a short capillary 

 tube, then bent downward again, terminating in a flat disk having 

 a small hole in the center. This instrument he calls a stalag- 

 mometer, and by its means drops may be counted with an error 

 of not more than 0-2 of a drop in 100 drops. To use it the alco- 

 holic liquid to be tested is diluted to contain about 20 per cent 

 of alcohol by volume, the stalagmometer is filled with it, the 

 number of drops in the given volume counted and compared with 

 the corresponding number given by pure 20 per cent alcohol. 

 An excess in the former case of 1*6 drops in ]00 corresponds to 

 0*1 per cent fusel oil, of 3-5 drops to 0*2 per cent, etc. Since the 

 maximum error is 0*2 of a drop in 100, as small a quantity as 0*05 

 per cent of fusel oil can thus be certainly detected. In order to 

 increase the delicacy of the method, the author concentrates the 

 solution as follows : about 300 c. c. of the alcoholic liquor, pre- 

 viously diluted to a 20 per cent strength, is placed in a stoppered 

 separating funnel furnished with a tap, from 110 to 120 grams of 

 pure ammonium sulphate is added and the whole is shaken, until 

 on standing for a minute or two, it separates into two well-defined 

 layers. The upper of these is diluted with water and two-thirds 

 of it distilled off. The distillate is made up to 100 c.c, its density 

 is determined, and after dilution to 20 per cent it is placed in the 

 stalagmometer and the number of drops compared with that ob- 

 tained with pure alcohol of the same strength. In a series of 

 comparative tests, fusel oil being added to pure alcohol to the 

 extent of 0-05, 0-10, 0'18 and 0-3 per cent respectively, the stalag- 

 mometer method gave 0-04, 0*07, 0*18 and 0-26 per cent. In gen- 

 eral, the influence of the compound ethers and etherial oils is too 



