G8 
ance. It is soluble in strong hydrochloric acid and in aqua 
regia, but is insoluble in water, nitric and sulphuric acids. 
Analysis of the residue gave the following results; 
Wt. tlm. 
gave 
% 
Avge. 
0*3897 grm.. 
..0*1696 grm. SnOo 
= 34.4Sn ] 
>34.46 Sn 
0*8214 „ . 
,..0*359 
5 ? 
= 34-52,, J 
0*3013 „ . 
0*5228 „ , 
,..0*2395 
...0*397 
„ MgNH 4 AsO,H.O = 29-96As ■ 
„ „ = 29-69 
j. 29-82 As 
0*7842 „ . 
0*852 „ 
...0*0801 
...0*099 
„ H,0 
= 10-21H,O 1 
= 11-02 „ J 
j. 10-91 H.0 
The simplest formula agreeing with tliese results is 
As Sii 0 H^O 
Found 29*82 34*46.,,... — 10.91 
Calculated ... ...29*46... ...34*76 25*18 10*6 
Professor Reynolds, M.A., exhibited and explained the 
action of a Geissler’s Light Mill. 
Ordinary Meeting, February 8th, 1876. 
Edward Schunck, Ph.D., F.R.S., &c., President, in the 
Chair. 
Mr. W. A. Cunningham and Mr. W. Brockbank were 
appointed Auditors of the Treasurer’s Accounts. 
Professor 0. Schorlemmer, F.R.S., read the following 
communication, which he received a short time ago from 
Professor SiDTLER, of the University of Pennsylvania : — 
“ Since I heard from you I have been analysing some of 
the natural gases from the gas wells in Butler County, 
Pennsylvania, in the midst of the oil region. 
“ This gas has been brought in lines of piping eighteen 
miles to Pittsburg, and is used with great success as fuel in 
the rolling mills there, so the Geological Survey sent me to 
collect and analyse it, 
