3<26 



ration, than wheat-starch. It is to the want of attention to these 

 circumstances that the author assigns the different results given by 

 chemists with respect to the composition of this principle ; which in 

 the abstract, or free from water, he considers as identical with cane- 

 sugar similarly circumstanced. 



The next principle considered is vinegar, a substance that in almost 

 all ages and countries, either by accident or design, has been more 

 or less used as an aliment. The author states that he had reason to 

 suspect long ago that the hydrogen and oxygen in this acid existed 

 in the proportions which form water, but that he was not completely 

 able to satisfy himself en the point till he employed the present ap- 

 paratus. He decided the point by means of the acetate of copper, 

 which produced no change of bulk in the oxygen employed. He 

 states this acid to consist of carbon 47'05, and water 52'95 ; results 

 that very nearly agree with those of other chemists. This principle 

 is not, however, in the protorganized state, except the acid found in 

 almost all animal matters, and hitherto called the Lactic acid, be 

 deserving of that appellation. 



The last substance connected with this series is lignin, or the 

 woody fibre, a principle subject to all the varieties of starch before 

 mentioned. The author finds the composition of this principle, in 

 the abstract, as containing carbon 57'14, water 52'86 ; and ob- 

 serves, that he is not acquainted with it in the crystallized state, but 

 that he has no doubt of its existence. In proof of the alimentary 

 qualities of this principle, he quotes the experiments of Professor 

 Autenrieth, of Tubingen, who states that when wood is reduced to a 

 minute state of division, and subjected to other processes, which he 

 describes, it is capable of gelatinizing like starch when boiled in 

 water, and of forming bread. 



The sugar of milk is next considered. This, in its crystallized 

 state, is composed of carbon 45 - 45, water 54*54. Gum-arabic, ac- 

 cording to the author, is this substance in the protorganized state, 

 and, like all analogous substances, combines with any proportion of 

 water ; arid hence the different compositions assigned to it by differ- 

 ent chemists. 



As connected with this subject, the author next proceeds to con- 

 sider the oxalic, citric, tartaric, and saccholactic acids, the compo- 

 sition of each of which is given ; and concludes by observing, that 

 he purposely refrains from all chemical observations, till the whole 

 of the facts in his possession are laid before the Society. 



Experiments to ascertain the Ratio of the Magnetic Forces acting on a 

 Needle suspended horizontally, in Paris and in London. By Captain 

 Edward Sabine, of the Royal Artillery, Sec.R.S. Read June 21, 

 1827. [Phil. Trans. 1828, p. 1.] 



The needles used in these experiments were cylinders O'ISth of an 

 inch in diameter, and 2'4 inches in length, pointed at the ends, and 

 suspended by a silk fibre 5 inches long, over the centre of a graduated 



