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400 Intelligence and Miscellaneous Articles. 



happy if this communication should determine others to try them. 

 The limits of this note compel me, also, to pass over in silence 

 many details intended to augment the chances of success. — Gomptes 

 JRendus de V Acad, des Sciences, vol. lxxvi. pp. 819-821. 



ON THE DEVELOPMENT OF HEAT BY THE FRICTION OF LIQUIDS 

 AGAINST SOLIDS. BY O. MASCHKE. 



It is known that the energetic aspiration of a liquid through a 

 porous substance is accompanied by a rise of temperature, probably 

 resulting from the friction of the liquid against the walls of the 

 capillary channels into which it rushes. M. Maschke gives some 

 measurements of the rise of temperature obtained by soaking amor- 

 phous silica with various liquids. 



The porous body, reduced to grains of the size of mustard-seed, 

 is introduced into a test-tube closed by a stopper with three aper- 

 tures, one of which gives passage to a thermometer, which measures 

 the temperature of the porous body and afterwards that of its mix- 

 ture with the liquid introduced ; another has a glass siphon which 

 dips to the bottom of the test-tube ; through the third an aspiration- 

 tube passes. By a prolonged stay in the same medium, the porous 

 body and the liquid are caused to have, at the commencement of 

 the experiment, sensibly the same temperature. The outer extre- 

 mity of the siphon being immersed in the liquid, the operator in- 

 hales gently through the discharge-tube, and observes the highest 

 temperature reached by the thermometer during the imbibing of the 

 liquid by the porous substance. 



M. Maschke has studied the following cases : — amorphous silica, 

 first moistened, then dried at a moderate temperature till it con- 

 tained only 39*8 per cent, of water, treated with water ; silica con- 

 taining 18'8 per cent, of water, and water ; dry silica and water ; 

 calcined silica exposed to moist air (22-68 per cent. H 2 O), and 

 water; silica calcined and then exposed to very moist air (28*24 

 per cent. H 2 0), and water • silica calcined and cooled over sulphuric 

 acid, treated sometimes with water, and sometimes with benzole, 

 oil of almonds, concentrated sulphuric acid, or alcohol. 



The experiment lasted 3, 10, 20, 30, and even as long as 45 mi- 

 nutes ; but it was not at the end of the experiment that the ther- 

 mometer immersed in the porous substance attained its maximum. 



The author operated at a mean temperature in the vicinity of 15° 

 or 20° C. In the majority of instances the rise of temperature 

 varied between 1° and 8° C. In the calcined and dry silica soaked 

 with concentrated sulphuric acid the thermometer rose from 19°* 8 

 to 33°'5. In one part of calcined silica mixed with 3*2 parts of 

 alcohol the thermometer rose from 13° to 26° C. Quartz and 

 pounded glass treated in the same manner give no appreciable rise 

 of temperature. — Archives des Sciences Physiques et JSfaturelles, vol. 

 xlvi. p. 271. 



