lilCIIARDS AND PARKKU. — ATOMIC WKIGHT OF MAGNESIUM. 59 



difficulty the form of apparatus used by one of us* in drying strontic bro- 

 niide was altered so that the boat could be transferred directly from the 

 ignition tube to the weighing bottle without an instant's exposure to the 

 outside air. In order to accomplish this result the hard glass tube was 

 ground with a long tapering joint directly into the wider desiccating or 

 cooling tube used to contain the weighing bottle. This desiccating tube 

 had a sort of bulb or " pocket" blown upon one side of it, to receive the 

 stopper of tiie weighing bottle, thus allowing the boat to be pushed past 

 the stopper directly from the ignition tube into the bottle. Afterwards 

 the stopper could be rolled into place with a rod provided for the pur- 

 pose. Tlie arrangement was used with great success in a recent deter- 

 mination of the atomic weight of zincf to which it was equally applicable. 

 A reference to the annexed sketch will make the apparatus more com- 

 prehensible. 



Fig. 1. — Bottling Apparatus, Horizontal Section. 



A — weighing bottle. B = stopper of bottle. C C = bard glass tube. 

 D= Platinum boat containing fused magnesic chloride. 



The desiccating apparatus for the hydrochloric acid gas consisted of 

 two towers, composed of a number of glass bulbs filled with beads, upon 

 which strong sulphuric acid was allowed to trickle from small reservoirs 

 at the top into suitable receptacles at the bottom. This apparatus was 

 constructed wholly of glass, with glass gridirons for flexibility, and ground 

 or sealed glass connections. Joints were made tight with syrupy phos- 

 phoric acid (Morley). The hydrochloric acid, after being evolved by 

 allowing strong sulphuric acid to run into a flask containing a strong 

 solution of hydrochloric acid, was passed through a wash bottle contain- 

 ing sulphuric acid, thence through the towers just described, afterwards 

 through a tube containing phosphoric pentoxide, and finally into the com- 

 bustion tube. The apparatus was so ari-anged that the current of air from 

 an aspirator could be passed through another set of towers, a duplicate of 

 those used for drying the acid gas. By means of stopcocks either dry 



* Richards, These Proceedings, XXX. 383. 



t Richards and Rogers, These Proceedings, XXXI. 158, 174. 



