On Gum Aralic and Gum Adraganth. 25y 



baryles, I conclude that the production ot" the soda has no- 

 thing to do with the presence of magnesia. 



But in the production of potash the presence of lime 

 seems to be essential, and, as you hinted, a portion of lime 

 must have been carried over with the distilled water; a fact 

 which few would suspect^ and which probably may often, 

 be the cause of differences in the results of chemical inves- 

 tigations, conducted^ to all appearance, in a snnilar manner. 



To determine the second point which I had in view ; 

 namely, whether the salts found in the residual water, or 

 any component part of them, came from the Galvanic bat- 

 tery by means of the conducting wires, I made similar ex- 

 periments to those before stated, enjploving for the decom- 

 position of the distilled water a powerful electrical machine- 

 instead of a Galvanic battery, but without obtaining results 

 different from what iiave been already stated. 



I am now enaaged in an experiment concerning the 

 formation of potash ; but, being desirous that my present 

 letter, which I write in haste, may reach you in time for 

 ttiis month's Magazine, cannot wait for its result. Should 

 the experiment succeed, you shall be informed as soon as 

 possible. In the mean time I remain, with the greatest 

 regard, yours, 



Cambridge, 

 Dec. '20, 1805. 



L. Experiments on Gum Aralic and Gum Adraganth. 



Bl/ M. VAUaUELIN*. 



1. X EN grains of red gum adraganth, furnished by com- 

 bustion three decigrammes and a half of white ashes. These 

 ashes dissolved in muriatic acid with effervescence, and 

 gave out an odour of sulphurated hydrogen. Their solution 

 gives by ammonia a precipitate which consists of phos- 

 phate of lime and oxide of iron. 'J'he oxalate of ammonia 

 precipitates a considerable quantity of lime. 



Thus the red gum adraganth contains in a hundred 

 parts about three and a half of ashes, which are con)po3ed, 

 for the greater part, of carbonate of lime, of a small quantity 

 of iron, of phosphate of lime, and perhaps also a minute 

 portion of alkali. 



a. Ten grains of white gum adraganth, submitted to the 

 -;ame proofs, yielded three decigrammes of ashes, which 



• From tiie .1'<n'ilvs Jc Cliimtc, torn. liv, 



l{ o wert! 



