480 SCIENTIFIC KECORD FOR 1882. 



ments of minerals weighing from one to five decigrams, have devised 

 a simple apparatus for the purpose, the minute rise of temperature, when 

 the body, previously heated, is placed in a liquid, being determined by 

 means of a thermo-electric couple. [Comptes Rendus, Jane, xciv, p. 1512.) 



Louguinine has described a new and improved form of calorimeter, 

 the results of which appear to be very satisfactory. {Ann. Chim. Phys., 

 November, Y, xxii, p. 398.) 



Yiolle has proposed an apparatus for applying the cooling method to 

 the determination of the specific heat of bodies when the initial temper- 

 ature of the body is between 100° and 500°. It consists of a small bot- 

 tle of thin glass, with double walls and a straight neck, a good vacuum 

 being made in the annular space. An agitator is introduced through the 

 neck by the side of the thermometer. {Comptes Bendus, June, xciv, 

 p. 1570.) 



Schuller has redetermined the heat of combination of water, in con- 

 sequence of certain criticisms of Von der Than. The oxygen and hydro- 

 gen meet in a combustion chamber formed of two parts ; they unite in 

 the upper part, which is at 225°, evolving (1) Mi calories employed to 

 heat them, (2) their heat of combination E, and (3) M2 calories corre- 

 sponding to the condensation of three volumes to two. The vapor of 

 water formed passes into the lower part at 0°, where it gives up M, 

 calories. Hence Ep= — Mi + E + M2 + M3. In this way the author finds 

 E=28810. ( Wied. Ann., V, xiv, p. 226; J. Phys., April, II, i, p. 192.) 



Louguinine has published an extended memoir on the measurement 

 of the heat of combustion of organic bodies, giving a description of the 

 apparatus employed, the mode of using it, and some of the results which 

 have been obtained with it. {Ann. Chim. Phys., November, V, xxvii, 

 p. 347.) 



LIGHT. 



1. Production and Velocity. 



Kruss has called attention to the fact that if the screen of a Bunsen 

 photometer be moved between two fixed sources of light, there are two 

 positions of this screen in which the fatty spot disappears. Both theory 

 and experiment show that the true ratio of the intensities from the two 

 sources is the geometric mean of the ratios calculated from both meas- 

 urements. {J. Phys., April, II, i, p. 201.) 



A new photometer has been constructed by Sabine, in which a wedge 

 of neutral tint glass is used to measure the intensity of a given light 

 by equalizing it with a standard paraffin flame. To secure greater 

 range *i set of diaphragms is used to regulate the amount of light com- 

 ing from the standard. {Nature, December, xxvii, p. 201.) 



Crova and Lagarde have made an improvement in the spectropho- 

 tometer whereby the illuminating power of simple radiations may be 

 compared. The illuminating power of a simple light they regard as the 



