DR. EDWARD C. EDGAR ON THE ATOMIC WEIGHT OF CHLORINE. 5 



chlorine under pressure in the former experiments that it was employed unhesitatingly 

 in these. 



The weights of chlorine condensed in each experiment varied between 70 and 

 80 grammes. 



5. The Method of Weighing. For the various weighings I used a short-armed 

 halance made specially for this work by Oertling. Even in weighing the steel bomb 

 (weighing considerably over 1000 grammes) the concordance of individual weighings 

 showed that their mean could be relied on to O'OOOl gramme. 



Each piece of apparatus weighed was counterpoised by another of the same material, 

 and of very nearly the same volume and weight. The weights employed, though they 

 had been standardised for the previous work, were carefully re-standardised for this ; 

 but the variations found were too insignificant to affect results calculated from the 

 older values. 



The details of the method of weighing are given in full in the former paper. It may 

 be noted here that the variations in volume of the palladium bulb, caused by the 

 differences in sealing off the thick-walled capillary tube, were small. In all the 

 experiments the bulb and its counterpoise differed so little in volume that, though the 

 density of the air in some of the determinations altered appreciably between the first 

 and second weighings of the bulb, in no case was it found necessary to apply a 

 correction to the apparent weight. 



6. The Combustion Appa/ratus. The chlorine was burnt in the quartz combustion 

 vessel A (shown in fig. 3, and, on a larger scale, in fig. 4), a prominent feature of 



Fig. 3. 



which was the dependent vertical limb B in which hydrogen chloride could be 

 condensed. The vessel had a capacity of 350 c.c. and was fitted with five ground 



