MINEEAL OE INOEGANIC POISONS 71 



of iron, stated as equivalent to 285 drachms of iron per- 

 chloride per 1*5 gallons of liquid contents. As regards 

 this case the effect must be ascribed to the astringent and 

 irritant action of the perchloride on the alimentary system. 



PHOSPHORUS. 



Chemical Characters. — Of the numerous derivatives of 

 the element, only the ' ordinary,' free, or white phosphorus, 

 and less frequently the hydride, and hypophosphorous acid 

 are of significance in toxicology. Poisoning by the very 

 highly toxic hydride is not likely to occur outside the 

 laboratory, although, when calcium carbide contains traces 

 of calciwfh- phosphide, phosphoretted hydrogen is given by 

 the action of water; and, moreover, calcium phosphide 

 itself is a moderately accessible substance. 



Ordinary phosphorus forms a waxy solid, of charac- 

 teristic garlic odour, very inflammable, and oxidised rapidly 

 with emission of a glow in the dark. Eed, or amorphous, 

 phosphorus is formed from the ordinary on heating, is 

 insoluble in oils and carbon bisulphide, and is not toxic. 



Ppeparations. — Those most likely to be met with are 

 phosphorus rat and mice pastes, which are made by incor- 

 porating finely divided phosphorus with a suitable grease, 

 and colouring with blue. Although often marked as non- 

 poisonous to cats and dogs, most of the accidents with these 

 animals and fowls are due to them. The grease protects 

 the phosphorus from rapid oxidation and spontaneous 

 ignition, and also facilitates its absorption on ingestion. 

 Phosphorus matches are less likely vehicles, and are being 

 rapidly superseded by so-called ' safety matches,' whose 

 heads are free of phosphorus. 



Toxic Dose. — Great uncertainty exists as to the toxic dose 

 of phosphorus, and the figures given are to be accepted with 

 reserve. A great deal depends on the state of subdivision, 

 a more finely divided preparation being more easily ab^ 

 sorbed. It has, indeed, been stated that coarse particles 



