iSiaJ Royal Society. " fB 



At the time of the election, the Society consisted of 60S 

 Members ; namely, 565 Ordinary Fellows, and 43 Foreign 

 Members. 



Dec. the lOth, a paper on ulmin, by Mr, Smithson, was 

 read. Mr. Smithson was induced to make his experiments, in 

 consequence of the account of ulmin ])ubli.^hed in Dr. Tliom- 

 son's System of Chemistry. Fie had received a portion of the 

 same ulmin from Palermo, upon which Klaproth had experi- 

 mented ; and it was npon this portion that his experiments were 

 made. This circumstance renders Mr. Smithson's observations 

 peculiarly valuable. They differ, indeed^ but little from the 

 account of ulmin given in an article contained in this very 

 number of our journa], which was printed before Mr. Sniitijson's 

 paper was read. But as tlie experhneiits of Dr. Thomson were 

 made upon English ulmin, it might have been objected that the 

 reason why they did not correspond with those of Klaproth was, 

 that the substance which he examined was of a different nature. 

 The experiments of Mr. Smithson quite destroy this objection. 

 He observed, that the solution of ulmin in water redden^.d 

 vegetable blues. This is a very remarkable ch'cumstance, if we 

 consider the quantity of potash which ulmin contains, and can 

 only be accounted for by supposing the potash saturated v ita an 

 acid. The most probable acid is the acetic. The ulmin exa- 

 mined in Article IIL of this number did not redden vegeta -le 

 blues; so that in this respect the two specimens differ materially 

 from each other. They seem to differ also m the propoiUcn of 

 potash; the English ulmin containing more than the specimen 

 from Palermo. Mr. Smithson considers ulmin as approaching 

 very nearly to extractive in its properties^. Tiiere can be no 

 doubt of the truth of the remark. Extractive, like ulmin, is pre- 

 cipitated from its solution in water by acids, and by several 

 metalline salts. But there is one difference between extractive 

 and ulmin too striking to admit them to be classed together. 

 Extractive dissolves in alcohol, but ulmin i^ insoluble in that 

 liquid. It is doubtless true, that species of extractive can be 

 named that refuse to dissolve in alcoliol. But this only shows 

 that at present very dissimilar bodies are classed together impro- 

 perly, under the name of extractive, and that the class should be 

 divided into at least two new genera ; and we may di; tinguish 

 these genera by the names of extraci'we and idm'm. 



Dec. 17. A paper on freezing at a distance, by Dr. VVollaston, 

 was read. The author began by meotioDlng the well-known fact 

 respecting the latent heat necessary to convert water into ice, 

 (140 degrees), and that which converts water into steam (960 de- 

 grees), and explained by that means the lowering of the tempe- 

 rature of water, which takes place by evaporation. To freeze 

 water by the air-pump, a very complete vacuum is requisite, and 



