66 Scientific Intelligence. 
substance to be examined equal to its molecular weight in milli- 
grams. These tubes, as in Hofmann’s method for vapor-densities 
ith a 
Bo ea and all the subsequent calculation, are avoided. The only 
difficulty seems ane lie in the accurate weighing; but, practically, 
this is no object since the weighing of liquids is effected in 
small bulbs, a it ‘is sufficiently accurate if carried to ae 
The tubes are calibrated easily by pouring into each of them 
weighed quantity of mercury, about equal in volume to that of 
the vapor to be estimated. If the mercury does not stand at the 
same height in both, gradually push a glass rod into it in the 
larger tube until the same level is reached. Mark carefully the 
point to which the rod is immersed, cut it off at this place, and 
allow the piece to rise to the top of the mercury in that tube 
excellently well . as a lecture experiment.— Ber. ta Chains 
Ges., v, 597, June, 1872. <a 
i ‘On the ined action of Heat and Pressure on tues ifjin.— 
In a second paper on this subject, Toorre and Youne give the 
subake ‘ot distillation under rete of 34 kilos. of paraffin made 
rom e, which melted at 46° and was composed of C 85.14, 
H 14.81. About 4 litres of fiuid hydrocarbons were aed of 
which 0.3 liter boiled below 100°, 1 liter between 100° and 200°, 
and 2.7 litres between 200° an 300°. The marsh gas series and 
eans of bromine. Of the former, pentane, hexane, heptane, 
octane, and nonane were obtained. Of the latter, the ‘brominated 
derivatives of the corresponding olefines. Paraffin undergoes @ 
similar decomposition to butane and other members of the mars rsh 
gas series.—_Ber. Berl. Chem. Ges., v, 556, July, 1872. G. F. B. 
Il. Geotocy anp Natrurat History. 
