RICHARDS. — RETENTION AND RELEASE OF GASES. 



405 



doned. All the subsequent ignitions were performed in a double cruci- 

 ble arranged in the manner shown in the diagram, the low platinum 

 crucible or capsule used to contain the cupric oxide, being protected 

 from radiation and convection by a number of superimposed crucible lids._ 

 The outer glazed porcelain cruci- 

 ble and the layers of asbestos 

 board covering the draught holes 

 united in excluding the products 

 of combustion of the illuminating 

 gas from the contents of the in- 

 ner capsule. By means of this 

 furnace, fed with a constant gas 

 supply burning from a fourfold 

 Bunsen burner, a surprisingly 

 constant and uniform tempera- 

 ture may be maintained for an 

 indefinite length of time. 



In the following table are 

 given the new series of results 

 showing: the relation of the total 

 volume of gas retained to the 

 temperature used in the ignition 

 of the cupric oxide. The gas 

 volumes are reduced to 0° and 760 mm. pressure, the reduction having 

 been made by means of a Winkler-Lunge corrector arranged to give 

 directly the exact volume of a mass of moist air which would measure a 

 hundred cubic centimeters when dry and under standard conditions. 



The Effect of Temperature on the Total Amount op Gas 



OCCLUDED BY CuFRIC OxiDE. 



First Series : First Preparation of Cupric Oxide. 



(1) 1 gram CuO, heated 1 hour at 300° ±,* gave 0.18 c.c. gas. 



(2) " " " " 0.19 



(3) " " " " 0.21 " 



I'lGURE 1. 



Average 0.19 c.c. gas. 



(4) 1 gram CuO, heated 4 hours at 500° ±,t gave 0.69 c.c. gas. 



(5) " " " " 0.72 



Average 0.70 c.c. gas. 



* Mercury thermometer. 



t Plumbic chloride just fused ; argentic iodide remained solid. 



