149 



! f 00 



= I 



2* J - 



gives the solution of the problem. 



The above-mentioned formulae are selected out of a great number 

 of very general results contained in the memoir. 



III. Letter from Dr. W. BIRD HERAPATH to Professor STOKES, 

 " On the Detection of Strychnia by the formation of lodo- 

 strychnia." Communicated by Professor STOKES, Sec.R.S. 

 Received June 12, 1856. 



Bristol, June 7, 1856. 



MY DEAR SIR, "Will you do me the favour to announce to the 

 Royal Society, that I have been engaged during some time past in 

 the application of my discovery of the optical properties of iodo- 

 strychnia to the detection of this alkaloid in medico-legal inquiries ? 

 I find it is perfectly possible to recognize the 10,000th part of a 

 grain of strychnia in pure solutions by this method, even when 

 experimenting on very minute quantities. In one experiment I took 

 ToW-h f a g ram om "yj an d having produced ten crystals of nearly 

 equal size, of course each one, possessing distinct and decided optical 

 properties, could not represent more than the x o o^ 1 P art f a 

 grain ; in fact, it really represents much less, inasmuch as one por- 

 tion of the strychnia is converted by substitution into a soluble 

 hydriodate, and of course remains dissolved in the liquid. 



I had hoped to have been able to complete this matter during 

 this summer, but I now find it impossible to do so in time for this 

 session of the Royal Society. I trust to be able to do so before 

 Christmas, however. Will you oblige me by getting this notice 

 inserted in the 'Proceedings,' as a new test for strychnia at this junc- 

 ture possesses considerable interest, the colour- tests having been so 

 dubiously spoken of recently by toxicologists ? 



In order to operate in this experiment, it is merely necessary to 

 use diluted spirit of wine, about in the proportions of one part of spirit 



