I 



Dr. Woods on the Heat of Chemical Comhination. 65 



its solubility. It is more soluble in hot hydrochloric and sulphuric 

 acids than in water, and is precipitated, apparently unchanged, on 

 the addition of water. Its alcoholic solutions give no precipitate 

 with aramonio-nitrate of silver, or with basic acetate of lead. 

 When gardenine is digested with concentrated nitric acid, it is 

 rapidly decomposed ; nitropicric acid, but apparently no oxalic acid, 

 being produced. 



Unfortunately, from the very small quantity of resin at my dis- 

 posal, I was unable to prepare a sufficient amount of the gardenine 

 either to subject it to analysis or to examine it more particularly. 

 Dr. Royle has, however, commissioned a large quantity of the resin 

 from India, which I trust will ere long enable me to complete its 

 examination. Gardenine appears to belong to the tolerably nume- 

 rous class of indifferent crystallizable resins, of which it is certainly 

 one of the most beautiful. 



January 10, 1856. — Admiral Beechey, V.P., in the Chair. 



The following communication was read : — 



*' On the Existence of Multiple Proportion in the quantities of 

 heat, or equivalent alteration of internal space of bodies, caused by 

 definite changes of state as produced by Chemical Combination or 

 otherwise." By Thomas Woods, M.D. 



Gay-Lussac having shown that the combining proportions of 

 gases and vapours are either equal in volume or some multiple of 

 each other, and other chemists, particularly Playfair and Joule, 

 having extended the same law to sohds and liquids, it is evident 

 that specific volume of its combining equivalent is characteristic of 

 matter. But as every substance is composed of matter and space, 

 or of particles with some distance between them, as is shown by ex- 

 pansion and contraction, whenever volume is altered there must be 

 either an addition to or subtraction from the internal space of the 

 body. This alteration of volume is evident in the case of bodies . 

 expanding or contracting by gain or loss of heat ; but in chemical 

 combination, where alteration of internal space must take place also 

 (as shown by change of temperature, and because specific volume 

 being characteristic of matter, this volume must change when the 

 matter changes, by a substitution of a mixture of two kinds of matter 

 for one), in chemical combination, I say, this alteration of internal 

 space is not so plainly demonstrable. Still, in the change of tempe- 

 rature, we have not only an evidence, but a measure of the change 

 of state of combining bodies. For, the phenomena of heat being 

 produced by a dual force acting equally in opposite directions, one 

 body cooling or contracting as another becomes heated or expands, 

 it may be taken for granted that whenever heat or expansion is found 

 in one body, the opposite change is occurring in some other. Now, 

 regarding this proposition as true, it is intended to be proved from 

 the combinations of oxygen that the internal space of a substance is 

 lost and gained in multiple proportion, in the definite changes of 

 state of bodies, such as in the condensation of vapours into liquids, 



Phil Mag, S. 4. Vol. \%, No. 7Q, July 1856. F 



