62 
holder, the internal pressure frequently projecting some of 
the liquid contents of the tube into the gas-holder, where in 
contact with the water ; decomposition took place with the 
formation of marsh gas, it being impossible to decompose all 
the zinc-methyl. 
The di-methyl thus obtained on treatment with chlorine, 
&c., yielded a small quantity of a liquid which began to boil 
at 11° C., and rose above 80° C. The quantity was, how- 
ever, but small, in consequence, no doubt, of the presence of 
marsh gas derived from the zinc-methyl, which was carried 
over by the pressure of the gas in the tubes ; and, as it 
became apparent that considerable difficulty would be en- 
countered in preparing large quantities of the pure gas by 
this method, it was abandoned. 
An analysis of this gas, according to Bunsen’s method, 
shows that pure di-methyl is to be obtained by this method; 
Found. 
Calculated for 
Di-methyl. 
Gas employed 
16-71 
Contraction 
42-30 
41-77 
Carbonic acid 
33-50 .... 
33-42 
I cannot conclude this communication without expressing 
my thanks to Professor Roscoe and Mr. Schorlemmer for 
the very able assistance rendered to me throughout this 
research. 
“ On a Property of the Electric Current to Control and 
Render Synchronous the Rotations of the Armatures of a 
number of Electro-magnetic Induction Machines;” Illus- 
trated by Working Models; by Henry Wilde, Esq. 
The discovery of the property which the author describes 
arose out of the efforts which have been made, during the 
last two years, to reduce the internal heat generated in 
large electro-magnetic machines by the rapid magnetization 
and demagnetization of the armatures. By constructing the 
machines of smaller dimensions this heating was consider- 
