CHEMICAL SCIENCE. 233 



When the temperature of the bath has reached 122 F., for instance, I 

 gradually cool the tube to 32, when the mercury contracts and the gas 

 takes the place of the expelled mercury. I then withdraw the point 

 from the current of gas, and immediately close it by sealing it at some 

 millimetres from its aperture. The tube thus charged is replaced in 

 the bath, which is again raised to 122, then gradually higher, and the 

 state of the gas observed in the capillary portion situated out of the bath 

 at the ordinary temperature. In this manner I have condensed chlo- 

 rine and ammoniacal gas, the bath for the latter being at the tempera- 

 ture at which the mercury filled the tube, the chlorine slightly below 

 it in a tube full of sulphuric acid. Carbonic acid in a tube full of mer- 

 cury at 122 F., becomes liquid at 131, the temperature of-the bath, if 

 the tube is very thick, otherwise at 138, and at a lower temperature 

 by pouring a few drops of ether over the end. 



" These experiments are free from danger; the only precaution ne- 

 cessary is to have the tubes well drawn out ; they then always burst in 

 the widened part rilled with mercury, which is accompanied with no ex- 

 plosion or projection. This method furnishes us an easy means of 

 showing on a small scale the liquefaction of gases. Barometer-tubes 

 somewhat strong, and the use of sulphuric acid in default of mercury, 

 answer perfectly well. I have tried to apply this method to those 

 gases which have hitherto not been liquefied. For this purpose I filled 

 three tubes, one with deutoxide of nitrogen, a second with carbonic ox- 

 ide, and the last with oxygen ; the tubes were filled with mercury at 

 122, and the bath raised to 140 ; the first tube then burst, while the 

 two others did so at 158. There was no trace of liquefaction percep- 

 tible. Perhaps by carrying the pressure nearly to the bursting of the 

 glass, especially with the assistance of a powerful refrigeration, new 

 results may be obtained by this method. If want of success by this 

 plan, which enables us to obtain almost indefinite pressure, should con- 

 tinue, we should probably conclude, as Mr. Faraday has already hinted, 

 that pressure alone is not capable of effecting the liquefaction of gases 

 under certain conditions of temperature." 



ON THE QUANTITY OF ASH CONTAINED IN VARIOUS KINDS OF 



WOOD. 



CHEVANDIER has communicated the following as the mean results of 

 a great number of determinations of the average amount of ash con- 

 tained in various kinds of wood, dried at 140. 



Ash given by 100 Paris of Wood. Average Amount of Ash given by all Kinds of Wood. 

 Willow . . 2.00 100 parts wood from young stems 1.23 

 Aspen . . . 1.73 " " Stock-wood . . 1.34 

 Oak . . . 1.65 " " Branches . . . 1.54 

 Alder . . . 1.38 " " Twigs . . . 2.27 

 Red Beach . . 1.06 

 Pine . . . 1.04 

 Fir . . . 1.02 

 Birch . . . 0.85 



20* 



