142 Notes and Queries. [No. 7, new series, 



" Query No. 5. A peculiar concretion resembling lime or gyp- 

 sum is occasionally found in the heart of teak logs. It generally 

 collects in what carpenters call a " shake" in the wood, but with 

 this exception the logs are perfectly sound, and no communication 

 whatever with the external air has been observed. Is its chemi- 

 cal constitution the same as that of the " tabasheer" or bamboo 

 salt. (Mr. Hawkes). 



Reply by J. E. Mayer, Esq., Professor of Chemistry Madras 

 Medical College. 



In answer to' the foregoing I beg to submit the following re- 

 port of an examination of a Calcareous found in the rift of a log 

 of Teakwood. 



The Chemical composition of the white incrustation enveloping 

 what has been ascertained to be woody fibre is the following. 



Bases. Acids. 



Iron. Carbonic. 



Lime. Silicic. 



Magnesia. Phosphoric ? 



Potash. Scarcely perceptible trace. 



The examination not having been quantitative, the expressions 

 employed to indicate quantities are merely approximative and com- 

 parative. Thus the base present in largest amount is certainly 

 magnesia, but the percentage though probably exceeding 50 parts 

 of the whole can only be thus suggested in like manner silicic acid, 

 is in considerable amount while the carbonic acid is in small 

 quantity, and the phosphoric in an inappreciable one, reverting to 

 the remaining bases, iron, is present in small amount, so is lime, 

 potash in somewhat larger quantity. 



The substance formed by the bases and acids above specified, 

 may be regarded as a natural kind of calcareous cement, not very 

 dissimilar to our mortars except that it possesses a larger amount 

 of silicic acid in a soluble form. The substance as a whole must 

 be looked on a mixture, and not a true chemical compound, 

 though containing such compounds, viz. carbonates and silicates 

 of magnesia and lime and potash of which indeed the substance 



