v.— C HEMISTEY. 



Art. LVI. — On the Bromine Metlwd of Estimating Sulphtir 

 in Gaseous Compounds. 



By Dr. W. P. Evans. 



[Read before the Philosophical Institute of Canterbury, 30th November, 



1896.] 



A SLIGHT modification of the well-known Harcourt method of 

 estimating sulphur in coal-gas seems capable of rendering 

 good service in the analysis of gaseous substances in general. 



For coal-gas a very simple form of apparatus gives ex- 

 cellent results. The gas is passed at the rate of about 

 25 litres per hour through any convenient form of absorption- 

 flask; then through a combustion-tube packed for about Gin. 

 of its length with platinised asbestos, and kept at a good red 

 heat ; and lastly through a second absorbing-flask (Winkler 

 spirals or ordinary 10- bulb tubes answer extremely well as 

 absorbing-flasks). The two flasks are charged with bromine 

 water acidulated with hydrochloric acid. The first flask gives 

 those sulphur compounds which are directly oxidized by bro- 

 mine water, the second those which are only oxidized after 

 passing the layer of heated platinum. 



In coal-gas this practically means that No. 1 gives the 

 sulphuretted hydrogen and No. 2 the carbon-bisulphide. If,^ 

 as is generally the case, only the total sulphur is needed, then 

 the first absorbing-flask is, of course, to be omitted. The 

 apparatus, once set up, needs no further attention. The only 

 precipitate is the well-known barium-sulphate, and the results 

 obtained are more than accurate enough for any technical 

 purpose. 



Art. LVII. — Befraction and Bejlexion of x-rays. 



By Dr. W. P. Evans. 



[Read before the Philosophical Institute of Canterbury, 30th November, 



1896.] 



While taking an x-ray photograph of a set of chemical 

 weights a very unlooked - for result was obtained. The 

 weights were of the cylindrical pattern, and had excep- 

 tionally well-polished surfaces. They were placed in two 



