478 SCIENTIFIC RECORD FOR 1882. 



of the temperuture coefficient of friction from that calculated from 

 theory cannot have lor its cause (at least not alone) the decrease of the 

 molecular diameter with rising temperature. {Wied. Ann. xiv, 232; 

 Nature, January, xxv, p. 290.) 



Dahlancler has ascertained that the velocity with which a body cools 

 in a liquid is: (1) uearly independent of its depth below the surface; 

 (2) is inde])endent of the nature of its surface ; (3) is dependent on its 

 excess of temperature ; and (4) for the same body in the same liquid 

 with the same excess of temperature it increases rapidly with the tem- 

 perature of the li(iuid. {J. Fhyn., September, II, i, p, 435.) 



Hill has calculated from data obtained by actinometric observations 

 in India, that the true absorbent of solar heat in our atmosphere is 

 aqueous vapor, the absorbing power being identical with that obtained 

 by Violle from measurements taken by himself in the Alps. [Proc. Boy. 

 Soc, XXXIII, p. 216 ; J. Phys., June, II, i, p. 290.) 



Heine has measured the absorption of radiant heat by gases by 

 means of the expansion produced. The gas is contained in a brass vessel, 

 whose sides carry plates of rock salt, through which pass the radiations 

 of a Bunsen burner. A very delicate manometer registers automatically 

 the variations of interior pressure. If air be used purified from water 

 vapor and carbon dioxide no change of pressure takes place, but if car- 

 bon dioxide be employed there is an increase of pressure resulting from 

 the absorption of heat by the gas. On mixing definite quantities of 

 carbon dioxide with air, definite curves were obtained, which were suffi- 

 ciently well marked to jiermit of the solution of the inverse problem ; 

 i. e., the determination of the carbon dioxide in the air from the absorp- 

 tion curves. The results agree well with those of chemical methods. 

 (J. Phys., August, II, I, p. 380.) 



Ferrini has experimented with the Crookes phenomenon, using two 

 similar tubes, one of which was exhausted only moderately, the spark 

 passing direct from one electrode to the other, while the other contained 

 air at the extreme of rarefaction. A Holtz machine furnished the elec- 

 tricity, tubes of rubber tilled with mercury being the conductors. One 

 of these was directly attached to the machine. The other was adjus- 

 table near the surface of mercury in circuit with the machine, so that 

 when it was immersed a continuous current was sent to the bulbs, and 

 when out of the mercury a longer or shorter spark could be obtained. 

 When these discharges passed through the low vacuum tube, the phe- 

 nomena varied like those observed by Hittorf, who used a constant cur- 

 rent, but varied the rarefaction; being due to the increase of the resist- 

 ance in the vicinity of the negative electrode as tlie ])0tential rises. The 

 resistance of the second globe was very m uch grea ter ; but the phenomena 

 from one globe to the other, vary in the same direction in which they 

 vary for the first globe when the difference of potential is increased. The 

 author rejects, consequently, the hypothesis of a fourth state of matter. 

 (II Nuovo Cimcnto, III, ix, j). 179; J. Phys.. November, II, i, p. 521.) 



