PROPERTIES. 34 1 



all circumstances, to assume a red tint ; to avoid which action 

 phosphorus is usually preserved in an opaque bottle. From its 

 solution in hot naphtha it may be obtained, in cooling, in re- 

 gular dodekahedral crystals. It is quite insoluble in water, 

 but soluble to a small extent, with the aid of heat, in fixed and 

 volatile oils, in sulphuret of carbon, of which 1 00 parts dissolve 

 20 of phosphorus, in chloride of sulphur, sulphuret of phos- 

 phorus, and ether. 



Phosphorus undergoes oxidation in the open air, and diffuses 

 white vapours, which have a peculiar odour, suggesting to some 

 that of garlic, and are luminous in the dark ; and at the same 

 time the phosphorus becomes covered with acid drops, which 

 arise from the phosphorous acid, produced in these circum- 

 stances, attracting the humidity of the air. This slow combus- 

 tion is attended with a sensible evolution of heat, and may 

 terminate in the fusion of the phosphorus, and its inflammation 

 with combustion at a high temperature. There is a necessity 

 for caution, therefore in handling phosphorus, a burn from this 

 body in a state of ignition being in general exceedingly severe. 

 It is preserved under the surface of water. The low combustion 

 of phosphorus has been particularly studied. It is not ob- 

 served a few degrees below 32, but is sensible at that tempe- 

 rature, and increases perceptibly a few degrees above it. The 

 presence of certain gaseous substances, even in minute quan- 

 tity, has a remarkable effect in preventing the slow combus- 

 tion of phosphorus \ thus at 66, it is entirely prevented by 

 the presence, 



Volumes of Air. 



of I volume of olefiant gas in ... 450 

 of 1 volume of vapour of sulphuric ether in. 15O 

 of 1 volume of vapour of naphtha in. . . 1820 

 of 1 volume of vapour of oil of turpentine in. 4444 

 and the influence of these gases or vapours is not confined to 

 low temperatures, a certain admixture of all of them defending 

 phosphorus from oxidation even at 200. But on allowing such 

 a gaseous mixture to expand, by diminishing the pressure upon 

 it to a half or a tenth, the phosphorus becomes luminous, and 

 the proportion of foreign gas required to prevent the slow com- 

 bustion must be greatly increased. The only explanation of 

 this phenomenon, which can be offered at present, is that the 

 gases which exert this influence have an attraction for oxygen, 



