604 



terms of the arsenic- and antimony-series, we designated this body as 

 the oxide of the phosphorus-base 



C 6 H 15 PO=(C 2 H 5 ) 3 PO*. 

 I have since confirmed this formula by actual analysis. 



The difficulties which in our former experiments opposed the 

 preparation of this compound in the pure state, arose entirely from 

 the comparatively small quantity of material with which we had to 

 work. Nothing is easier than to obtain the oxide in a state of 

 purity, provided the available quantity of material is sufficient for 

 distillation. In the course of a number of preparations of triethyl- 

 phosphine for new experiments, a considerable quantity of the 

 oxide had accumulated in the residues left after distilling the zinc- 

 chloride-compound with potash. On subjecting these residues to 

 distillation in a copper retort, a considerable quantity of the oxide 

 passed over with the aqueous vapours, and a further quantity was 

 obtained, as a tolerably anhydrous but strongly coloured liquid, by 

 dry distillation of the solid cake of salts which remained after all the 

 water had passed over. The watery distillate was evaporated on the 

 water-bath as far as practicable, with or without addition of hydro- 

 chloric acid ; and the concentrated solution was mixed with solid 

 hydrate of potassium, which immediately separated the oxide in the 

 form of an oily layer floating on the surface of the potash. The 

 united products were then left in contact with solid potash for 

 twenty-four hours and again distilled. The first portion of the 

 distillate still contained traces of water and a thin superficial layer 

 of triethylphosphine. As soon as the distillate solidified, the 

 receiver was charged, and the remaining portion about nine-tenths 

 collected separately as the pure product. To prevent absorption 

 of water, the quantity required for analysis was taken during the 

 distillation. 



With reference to the properties of oxide of triethylphosphine, I 

 may add the following statements to the description formerly given f. 

 This substance crystallizes in beautiful needles, which, if an appreciable 

 quantity of the fused compound be allowed to cool slowly, frequently 

 acquire the length of several inches. I have been unable to obtain 

 well-formed crystals ; as yet I have not found a solvent from which 



* H = 1 ; = 16 ; C = 12, &c. t Phil. Trans. 1857, p. 575. 



