86 
also protochloride of iron, which amounted to 16 grains per gallon, and 
was only known to occur in two other springs, both of which were on the 
Continent. Dr. Muspratt's remarkable results had been confirmed by Dr. 
Herapath himself, as well as by Prof. Miller, of King's College, London. 
The speaker illustrated his remarks with a number of preparations, showing 
the amounts of various substances obtained from given measures of the water, 
and also by a number of delicate tests which demonstrated the nature of 
the constituents, in the course of which operations he pointed out that the 
presence of protochloride of iron in any water materially interfered with 
the action of the permanganate of potash test for organic matter, the iron 
salt being rapidly oxidised just as organic matter would be. It had been 
proposed to give the name of Muspratt to the spring, in honour of the 
chemist who first made known this remarkable change in its character. 
Mr. W. L. Carpenter exhibited several beautiful specimens of carbo- 
lic acid, manufactured by F. C. Calvert, and Co., Manchester, and made a 
few remarks upon its manufacture and uses, pointing out its chemical 
relations to other known substances. 
He also showed a number of pieces of gun cotton, in various shapes, 
and for different uses, manufactured by T. Prentice & Co., Stowmarket, 
Suffolk. The speaker gave a short account of its mode of manufacture, 
and of the recent explosion at Woolwich. 
Rev. W. Whiting, apropos of gun cotton, described his process for 
preparing structureless collodion, in which the base of the pyroxiline was 
Swedish filtering paper. 
