change of volume has occurred on conversion of oxygen into 

 carbon or sulphur dioxide. 



The two bulbs on the limbs act as reservoirs for mercury, 

 otherwise it might be driven out of the tube owing to the 

 expansion caused by the combustion. 



83. Hof mann's apparatus for showing the constancy of 

 the proportions in which hydrogen and chlorine combine 

 to form hydrochloric acid gas. 



B. 262. 1877. Made by J. Schober, Berlin. 



This apparatus consists of a straight tube provided with end 

 stoppers and a stopcock at one-third its length. 



84. Hofmann's apparatus for illustrating the pheno- 

 mena of combustion. 



E. 268. 1877. Made by J. Schober, Berlin. 



This apparatus consists of a wide glass tube terminating at 

 the bottom in a narrow tube bent at right angles, and closed 

 above by a cork through which two tubes pass, one passing 

 just through the cork, the other, a narrow one, is provided with 

 a stopcock outside and ends inside in a platinum nozzle. The 

 gas which it is required to ignite is brought in through the 

 latter tube, the former being for the gas in which it is to burn. 

 By this apparatus oxygen may be caused to burn in hydrogen. 



85. Carbonic acid apparatus ; Geissler's, two forms. 

 Prices 4s. and 4s. 6d. 



1886. Exhibited by Townson Mercer. 



These are used for determining the amount of C0 2 in car- 

 bonates, by displacing it with an acid, such as hydrochloric or 

 dilute sulphuric. A weighed quantity of the carbonate is 

 placed in the small flask, the tube to run acid upon it is 

 filled with dilute acid, the bulb through which the displaced 

 CO 2 passes is filled with strong sulphuric acid, and the whole 

 is weighed. The dilute acid is then run upon the carbonate and 

 the apparatus warmed, so that all C0 2 is displaced but no water 

 as that becomes absorbed by the strong sulphuric, so that the 

 decrease in weight is entirely due to C0 2 liberated from the 

 known weight of carbonate introduced. 



86. Carbonic acid apparatus. Fresenius and Wills', 

 Kipp's, Orme's, Rose's, Schrotter's, Geissler's (two forms). 



1876 and 1887. Exhibited by J. Orme $ Go. 



87. Sulphuretted hydrogen apparatus, Kipp's. Price 

 7s. 6d. 



1876. Exhibited by J. Orme $ Go. 



