1867.] Chemistry. 245 



boiling solution of subacetate of lead. Part of the berberine separates 

 on cooling, and the rest is precipitated on the addition of nitric acid. 

 The nitrate may be decomposed by lime or ammonia, and the 

 alkaloid purified. The same process is applicable for the extraction 

 of theine from tea. 



At the meeting on the 7 th of February a note by Dr. Stenhouse, 

 "On some Varieties of Orchella Weed, and Products obtained 

 therefrom," was read. The author described the mode of obtaining 

 orcin and erythrite from Eocella tinctoria ; for details of which, and 

 also of a mode of determining the amount of colour-yielding 

 principles of lichens by the use of a standard solution of hypo- 

 chlorite of sodium, we must wait the publication of the paper. 



A note by Dr. Phipson, " On the Eggs of Corixa Mercenaria," 

 was also read. These eggs deposited on reeds in fresh-water lakes 

 in Mexico, by a kind of boat-fly, are ground by the natives and 

 used as food. They are chemically composed of chitine with a little 

 phosphate and carbonate of lime, Chitine, Dr. Phipson believes to 

 be a glucoside. The eggs are supposed to contribute to the for- 

 mation of a new oolitic limestone at the bottom of the Mexican 

 lakes. 



After this, Dr. Matthiesen gave an interesting lecture "On 

 Alloys." We need only say here that the author disputes the 

 notion that alloys are definite chemical compounds (except indeed in 

 one or two instances), and only regards them as intimate mixtures 

 of the metals. In some cases, however, in which the physical 

 properties of one metal are entirely changed by a small admixture 

 of another, the resulting alloys, it was said, could only be regarded 

 as solidified solutions of allotropic modifications of the metals in 

 each other. This view of the author was more fully developed 

 in his Eeport to the British Association, 1863. 



The last meeting we can notice was held on March 1, on which 

 occasion Mr. E. T. Chapman read a paper " On Limited Oxidation : 

 the Determination of the Oxygen Consumed." Eeferring the reader 

 to the paper before noticed, we may say that a known quantity of 

 the chromic acid solution is titrated with oxalic acid, and the 

 resulting carbonic acid weighed. Another quantity of the chromic 

 solution is then digested with the organic body, as previously 

 described, and after digestion the solution is titrated in the same 

 manner with oxalic acid. The difference in the amount of carbonic 

 acid obtained, is the measure of the oxygen consumed. This 

 method was specially recommended for the estimation of alcohol, 

 and generally as a proved method in a great variety of quantitative 

 examinations. 



