366 Dr. Blyth on the Compositioti of Narcotine, 



the quantity of metallic platinum obtained per cent, was 22*45. 

 The white crystals were found to be identical with opianic 

 acid, already obtained by M. Liebig and Wiililer from nar- 

 cotine, by the action of peroxide of manganese and sulphuric 

 acid. 



It is probable that in determining the atomic weight of 

 narcotine from its platinum double salt, the error in most 

 cases arose from the employment of too great an excess of the 

 bichloride of platinum for precipitation, under the influence 

 of heat. Bichloride of platinum under these circumstances 

 acts just as any other oxidizing agent, being itself reduced to 

 the state of protochloride. In those instances in which the 

 per-centage of platinum is given high, it is likely that the salt 

 analysed was mixed with a portion of these red crystals con- 

 taining above 22 per cent, of platinum. 



To avoid these two sources of error, pure narcotine was 

 dissolved in dilute hydrochloric acid, and to the cold solution 

 just so much bichloride of platinum was added as was suffi- 

 cient for the precipitation. After removal of the fluid by the 

 Bramah press, the dry mass was pounded, again thrown on 

 a filter and washed with a small portion of distilled water. 

 The salt thus prepared should be dried at a temperature 

 below 100° C. In the following analyses different prepara- 

 tions were employed. 



I. 0*9905 grm. gave platinum 0*1585 = 16*00 percent.; 

 atomic weight calculated = 51 35. 



II. 0*9313 grm. gave platinum 0*1 486 = 15*95 per cent.; 

 atomic weight ::=: 5 159. 



III. 0*907 grm. gave platinum 0*142 = 15*65 per cent.; 

 atomic weight= 5304*67. 



IV. 0*947 grm. gave platinum 0*149 = 15*73 per cent.; 

 atomic weight= 5265*83. 



A salt carefully prepared by Dr. A.W. Hofmann gave from 



V. 0*7617 grm. 0*1208 of metallic platinum = 15*85 per 

 cent.; atomic weight calculated from this =5208. 



VI. 0*6272 grm. gave platinum 0*0991 = 15*8 per cent.; 

 atomic weight = 5232. 



The atomic weight adopted from the mean of the last three 

 analyses, which wei'e most carefully made, is 5235. With 

 this number I now attempted to construct a formula from my 

 own analyses of the double platinum salt, and from those of 

 narcotine itself made by M. Liebig, Pelletier and Regnault. 



I. 0*6535 grm. platinchloride of narcotine, burned with 

 chromate of lead, gave carbonic acid 1*0477, water 0*2455. 



II. 0*4025 grm, gave carbonic acid 0*643, water 0*156. 

 These correspond iu the hundred parts to 



