﻿482 Scientific Intelligence. 



tivity of ice and snow, the dilatation of pure iee, and its relative 

 penetrability at various temperatures. In experimenting in regard 

 to the first point a mass of water about 2 feet square and 1 foot 

 high was converted into ice by a freezing mixture and a uniform 

 temperature of 0° F. obtained. In place of the freezing mixture 

 fresh snow was then supplied and the gradual increase of temper- 

 ture noted by a series of thermometers until the whole mass was 

 at 32° F. This required 73£ hours. The experiment was then 

 repeated with pure snow lightly pressed together; 165 J hours 

 were required to bring it up from 0° F. to 32° F. The relative 

 conductivities obtained are expressed in a diagram, the conclusion 

 being that the conductivity of the ice was about 122 per cent 

 greater than the snow under the conditions of the experiment. 



The dilatation of ice was measured between — 35° F. and + 32° F. 

 The linear coefficients obtained are as follows : 



Linear coefficient for 1° between +16° F. and +32° F. = 0-000040876. 

 " " " " +16 " =0-000028042. 



" " " —21 " " =0-000020484. 



" " " -30 " —21 " =0-000019744. 



The hardness of ice at different temperatures between —35° F. and 

 + 32°F. was measured by the relative depths to which a blunt- 

 pointed steel rod with a weight of 181| lbs. on its top penetrated. 

 It was found that between — 35° F. and +10° or 20° F. the ice 

 was nearly impenetrable, the depth of penetration being only \ 

 inch at 10° and § inch at 20° ; after which the power of resistance 

 decreased rapidly with the temperature. — Proc. Roy. tioc, xl, 

 544, 1886. 



II. Geology and Natubal Histoky. 



1. On the gaseous constituents of Meteorites. — Ansdell and 

 Dewar have continued the work begun by Graham and carried 

 further by Mallet, Wright and others in regard to the gases 

 occluded in meteorites. The results of the analyses of the gases 

 in three meteorites are given in the following table, with which 

 those obtained from a piece of fresh pumice are compared : 



Occluded 



in vols. , 



Percent 

 CO 



age composition. — 

 H CH 4 



IP 



1-31 



5-40 



3-90 



18-50 



28-48 

 18-L4 

 22-94 

 254 



39 



7-65 

 4-41 



1-31 



2-69 



3-67 



16-60 



Sp. gr. of the meteorite. C0 2 



Dhurmsala .. 3-175 2-51 63-15 



Pultusk 3-718 3-54 66-12 



Mocs 3-67 1-94 64-50 



Pumice-stone, 2 50 0-55 3950 



In order to test directly the absorptive power of one of the 

 porous stony meteorites, a sample of the powdered Dhurmsala 

 stone, from which the gases had been already removed, was left in 

 moist air under a bell glass for a longer or shorter period. The 

 results are given for the different periods in the following table ; 

 the gases were drawn off at a low red heat after the time given in 

 each case: 



