378 
POPULAR SCIENCE REVIEW. 
uPxlike sliell-lac. The properties of this nev/ compound, which was pre]5ared 
by Mr. Spiller in sufficiently large quantities for chemical examination, v/ere as 
follows : — Freely soluble in alcohol, chloroform, wood-spirit, and benzol ; in- 
appreciably soluble in ether, bisulphide of carbon, and oil of turpentine ; 
readily soluble in alkalis, being precipitated from these solutions by acids ; 
is bleached by exposure to ammonia- water ; fuses below 212° Fahrenheit, 
and when strongly heated gives off a yellowish empyreumatic oil and water, — 
the latter demonstrating the presence of oxygen (1) ; brittle and electric at 
ordinary temperatures, and has, according to analysis, this composition : — 
Carbon... ... ... G4*00 
Hydrogen ... ... 8'46 
Oxygen... ... ... 27*54 
Gases produced in the Cementation of Iron. — Some very interesting facts 
relative to the nature of the gases developed during the processes of cemen- 
tation have quite recently been indicated in a memoir presented by M. 
Cailletet to the French Academy. The experiments of this investigation were 
carried out at the great factory of Drambon, by permission of MM. Guenard 
and Co. In order to collect the gases for examination, a hole was bored into 
one of the cases in which the iron is packed before it is submitted to heat, 
and into this aperture was fitted a porcelain tube. One of the extremities of 
this tube was plunged for a depth of 40 centimetres into the case, and to 
the outer end was attached a tube of glass. By means of this apparatus the 
gases were made to traverse a series of bulbs, and were finally collected in an 
aspirator specially arranged. After the fires had been burning for five hours, 
the aspirator was put in action, and the collected gases were analyzed by the 
simple method devised by M. Peligot. The following figures, which repre- 
sent the mean of tv/o analyses, were the results obtained : — 
Carbonic acid 
Carbonic oxide 
Hydrogen . . . 
Nitrogen 
20*06 
15*55 
26*60 
37*79 
100-00 
In a second inquiry, when the gases were collected sixty hours after the 
furnaces had been lit, the results were very different ; thus, omitting fractions, 
the nitrogen was in the proportion of 46 per cent., the hydrogen of 38, the 
carbonic oxide of 16 ; whilst there was not a trace of carbonic acid present. 
In every case the gases were washed prior to their examination, but the water 
gave not the faintest trace of cyanides. — Yide Comptes Rendus, Feb. 13. 
Removal of Sulphide of Carbon from Coal-gas . — Bisulphide of carbon has 
long been the bugbear of gas manufacturers, and it is therefore satisfactory 
to be able to record the discovery of a process for the pimfication of gas by 
the removal of this substance. Sulphide of carbon is a liquid and easily vola- 
tilized compound, of one equivalent of carbon and two of sulphur, and in 
combustion it is resolved into carbonic and sulphurous acids. Now, sul- 
phurous acid, besides being a vapour possessing the unpleasant smell of 
burning sulphur, has also other qualities of a highly detrimental character 
