138 Royal Society : — 



The analysis of the crimson crystals has shown that they contain 

 C^, H,. PS,=Cj, Hj5 P+C, S,=E3 p+a S,. 

 They are therefore formed by the direct union of 1 equivalent of 

 triethylphosphine with 2 equivalents of bisulphide of carbon. 



In the dry state the bisulphide of carbon compound may be pre- 

 served without being altered. In the presence of moisture, however, 

 it is decomposed, especially during hot weather. On examining 

 some specimens which had been kept during several months, the 

 crimson colour was found to have disappeared, the substance had 

 assumed a light yellow colour, and on opening the bottles the odour 

 of sulphuretted hydrogen became at once apparent. The yellowish 

 substance on recrystaUization proved to be pure bisulphide of tri- 

 ethylphosphine. I leave it undecided whether this transposition had 

 taken place according to the equation 



E3PaS, + 2HO=E3PS,+2HS + C,0„ 

 or 



E3PaS,+2HO + 20=E3PS,+2HS + aO,. 



What is the constitution of the crimson body? In mineral 

 chemistry we are acquainted with a compound closely allied in com- 

 position and formation to the new compound. Bisulphide of carbon, 

 when treated with an alcoholic solution of ammonia, furnishes, together 

 with other products, a salt crystallized in long lemon-yellow needles, 

 which is known by the name of sulphocarbamate of ammonium. 

 This compound, 



(H,N)H,N,aS„ 



when treated with diluted acids, is converted into an oily acid of but 

 little stability, sulphocarbamic acid : 



H H, N, C, S,. 



If we replace in this compound the hydrogen by ethyle, the nitrogen 

 by phosphorus, in other words, if we replace the ammonia by tri- 

 ethylphosphine, we arrive at the composition of the body which forms 

 the subject of this note. 



I have convinced myself experimentally that trimethylphosphine 

 exhibits with bisulphide of carbon a perfectly similar deportment. 

 The compound formed is likewise of a crimson colour, but of a some- 

 what lighter tint ; it is more volatile and more readily soluble in 

 alcohol than the corresponding ethyle-compouud : it is also somewhat 

 soluble in water. 



Triethylarsine is not altered by the addition of bisulphide of carbon ; 

 after some time, however, long needles are formed in the mixture of 

 the two bodies. These needles are probably an analogous arsenic- 

 compound : I have not however examined them. A mixture of 

 triethylstibine and bisulphide of carbon was preserved for several 

 months, without undergoing any change. 



"Contributions towards the History of the Monamines." By A. 

 W. Hofmann, Ph.D., F.R.S. 



The progress of my experiments on the poly-ammonias and on the 



