398 Royal Society .— 



the concentric space between the steam-tube and a wider tube iu 

 which the steam-tube was placed. The steam-tube was connected 

 at its lower end with a receiver to hold the condensed water. A 

 mercury gauge indicated the pressure within the apparatus. The 

 principal object of the author was to ascertain the conductivity of 

 the tube under varied circumstances, by applying the formula sug- 

 gested by Professor Thomson, 



r «, V 

 C=— log— , 

 a ° v 



where a is the area of the tube in square feet, w the quantity of 

 water in pounds transmitted per hour, V and v the differences of 

 temperature between the inside of the steam-tube, and the refrige- 

 rating water at its entrance and at its exit. The following are some 

 of the author's most important conclusions. 



1. The pressure in the vacuous space is sensibly the same in all 

 parts. 



2. It is a matter of indifference in which direction the refrigerating 

 water flows in reference to the direction of the steam and condensed 

 water. 



3. The temperature of the vacuous space is sensibly equal in all its 

 parts. 



-4. The resistance to conductivity must be attributed almost entirely 

 to the film of water in immediate contact with the inside and outside 

 surfaces of the tube, and is little influenced by the kind of metal of 

 which the tube is composed, or by its thickness up to the limits of 

 that of ordinary tubes. 



5. The conductivity increases up to a limit as the rapidity of the 

 stream of water is augmented. 



6. By the use of a spiral of wire to give a rotary motion of the 

 water in the concentric space, the conductivity is increased for the 

 same head of water. 



The author, in conclusion, gives an account of experiments with 

 atmospheric air as the refrigerating agent ; the conductivity is very 

 small in this case, and will probably prevent air being employed for 

 the condensation of steam except in very peculiar circumstances. 



December 20. — Major-General Sabine, Treas. and V.P., in the Chair. 



The following communication was read : — 



"Preliminary Notice of Researches into the Chemical Constitution 

 of Narcotine and of its Products of Decomposition." By A. Mat- 

 thiessen, Esq., and George C. Foster, Esq. 



I. Composition of Narcotine. 

 The announcement made by Wertheim* and Hinterbergerf of the 

 probable existence of various kinds of narcotine, rendered it necessary 

 to commence the present investigation by a series of analyses of our 

 material, in order to ascertain which variety of narcotine we were 

 dealing with. 



The narcotine employed was obtained from Mr. Morson, to whom 

 * Chem. Gaz., 1850, p. 141. f Ibid., 1851, p. 309. 



