On the Decompositiofi of the Miiriaie of Soda. 27 



I have only to observe, in addition to the«e particulars, 

 that the susceptibility by which prussiat of potash is trans- 

 mitted to the bladder, seems to vary in different individuals; 

 for in five trials, made at Guy's Hospital in Nov. 1S05, T 

 failed of discovering any vestige of that salt in the urine of 

 persons who had taken it in quantities sufficient to produce 

 its appearance in others. Three of these individuals, I 

 should observe, were at the time under mercurial treatment, 

 and an idea occurred to me that mercury having a great 

 affinity for prussic acid, the presence of that metal in the 

 system might prevent the effect in question. But as in the 

 two other failures no mercury was prescut, I cannot lay 

 afly stress upon that conjecture. It may be proper to men- 

 tion, that in the frequent trials which I have made with the 

 prussiat of potash, no symptom or inconvenience whatever 

 has ever occurred which could be ascribed to that salt. 

 I remain ever, my dear sir, 



with great esteem, yours sincerely, 



Alex. Marcet. 



P. S. — Whilst revising the proof of this sheet, it has beeri 

 observed to me by some friends, and in particular by Dr. 

 Henry of Manchester, and Dr. R. Peajson of London, that 

 in order to show distinctly that certain substances find their 

 way to the bladder without passing through the general 

 circulation, it would be necessary to examine the arterial, 

 as well as the venous blood, since it is not impossible that 

 the whole of the sugar in diabetes, or the prussiat of potash 

 in the experiments above related, may be conveyed to the 

 urinary organs by the arteries, without entering the venous 

 system. According to this hypothesis, it may be conceived 

 that the same substances when conveyed by the arteries to 

 distant parts of the body, may return by the absorbent sy- 

 stem, and might in that case be discovered in the thoracia 

 duct. Tliis view of the subject may deserve further inves- 

 tigation ; and I hope that this curious question will soon 

 be decided by appropriate experiments. 



IV. On the Decern position of the Muriate of Soda, hij means of 

 the IVaters flou ing from the Lixiiiation of the efflorescent, 

 pijritous Earths. By M. LEFRor, Alining Engineer*. 



J. HE soda used in France is almost entirely of foreign 

 jiianufaclurc; and the present maritinjc war, added to the 



• Juurnal dts Minet, vol. xxvii. p. 231. 



disturbances 



