276 
PROCEEDINGS 1849—1858. 
for the development of domestic heat as well as for illuminating 
purposes. The application of coal-gas for the production of heat, as 
well as light, is one which demanded strictest attention. The heating- 
value of gas, he considered, is greater than that of coal, and its 
application easy and economical. Amongst its advantages are the 
cheerful brilliancy of its flame, the facility with which the supply 
can be regulated and the temperature kept uniform, and the absence 
of smoke and soot. He cites, as an instance, Mr. Appold, the 
inventor of the centrifugal pump, who, at his residence near London, 
liad erected a small gas manufactory in one of his outbuildings, and 
used its products for every heating purpose throughout his entire 
premises. By introducing the gas at a number of small orifices, at 
the back of grates, he obtained a cheerful and exceedingly warm fire. 
Among other ingenious experiments he had provided each supply pipe 
with a throttle valve, so delicately suspended as to be opened or 
closed by the fall or rise of the thermometer, placed on the stairs 
leading to his rooms, and so admirably can he regulate the tempera- 
ture by this means, that it did not vary more than three or four 
degrees during the whole year. A suggestion might be taken from 
this for the regulation of the temperature in rooms heated by gas at 
the present time. The ammonia at that time was discharged into 
the atmosphere. iMr. Simpson suggested a most simple arrangement 
by which this important production might be economised, and under 
the form of sulphate of ammonia form a most valuable commercial 
article. He referred to an ingenious patent recently taken out by 
Mr. Crole, of the Tottenham Gasworks, by wliicli he passed the 
ammonia gas through a weak solution of sulphuric acid ; the gas 
uniting with the acid forms sulphate of ammonia in solution. This 
is evaporated to dryness, and yields 80 ounces per gallon, the com- 
mercial value of which is £13 per ton for the purposes of manure. 
It is needless to remark on the extent to which this operation 
is carried out in the gasworks now existing, and it is somewhat 
remarkable that the value of the sulphate of ammonia was so 
nearly the same at that day as the price now obtained . His paper 
concludes with a suggestion that in the manufacture of iron, large 
quantities of combustible gases are eliminated, as attested by the 
