150 Mud-Baths. 



greatest possible quantity of nutritious and tonic substances in 

 the smallest weight ? 



The colouring properties of the two substances are entirely 

 different. After the discovery, twelve or fifteen years since, of 

 the composition of the terra japo?nca, attempts were made in 

 England to introduce it into the materia lingentia, as a substi- 

 tute for galls ; but unfortunately, like the extract of quercitron, 

 it affords with iron nothing but a meagre olive; and Dr. Ban- 

 croft states, that in a great number of trials, he was unable, by 

 the greatest accumulation, to produce any thing like a black, even 

 upon wool, much less upon cotton and silk. 



A singular fact which I observed in the course of my experi- 

 ments is worthy of notice. I had prepared for a certain purpose, 

 solutions from the wood of the trunk of a tree about three feet, 

 and from that of a limb about three inches in diameter. The 

 same quantity of wood and of the solvent was employed in both 

 cases. On adding to each the same quantity of the solution of 

 gelatine, abundant precipitates immediately appeared, as usual, 

 apparently much the same in quantity ; but to my astonishment, 

 the size of the several congeries in each bore a near proportion 

 to that of the sticks from which they were obtained, not differing 

 much from t^^at of middling and of very small flakes of snow. Is 

 not this an extraordinary fact, evincive of a complication in the 

 arrangement of these bodies hitherto unsuspected ? May it not 

 at some future period lead to a nomenclature of' precipitates ; 

 affording, like the crystallography of Haiiv, anew and accurate 

 mode of determining the compositions of substances ; and per- 

 haps throwing light upon the obscure subject of chemical, or, if 

 you please, electro-chemical affinities ? The size of a stick might 

 probably be ascertained with almost as much precision, as by 

 actual admeasurement. The solutions in this experiment were 

 formed by maceration in cold water. When hot water was 

 employed, and the process was completed in two or three hours, 

 the appearance of the precipitate was very different, the conge- 

 ries being smaller, irregular, and not well defined. 



I have only to add, that having taken measures to secure the 

 discovery, both in this country and Europe, it is my wish to bring 

 it into general use as speedily as possible. 



I am, Sir, very respectfullv, your obedient servant, 



William Sheldon. 



MUD-BATHS. 

 [From Hallam's Letters from the Nortli of Italy. — Murray.] 

 The village of Abano is celebrated for its muds, which are 

 taken out of its hot basins and applied either generally or partially 



as 



