4'24 VKARUOOK OF THE DEPARTMENT OF AGRICULTURE. 



The chief objection to the use of phosphorus is the danger of serious 

 conflagrations. In the West, where phosphorus is extensively used 

 for killing ground squirrels, it has caused fires which destroyed entire 

 fields of ripe wheat and barley and buildings in which prepared 

 phosphorus was stored. Some hazard attends the use even of care- 

 fully prepared phosphorus pastes. Experiments with a commercial 

 paste containing l.G per cent of phosphorus showed that it could not 

 be ignited either by contact with flame or by friction ; but when stirred 

 after a few hours' exposure to the sun, it burst into flame. Another 

 sample of paste, containing less than 1 per cent of phosphorus, was 

 subjected to the same tests but could not be ignited. It was then left 

 out of doors over night, and rain washed out part of the glucose. The 

 residue, dried by exposure to sun and wind, soon charred and burned 

 through the paper on which it lay. 



ARSENIC. 



The qualities of arsenic as a poison are pretty generally understood. 

 In the form of Paris green or London purple it is widely employed 

 as an insecticide. It is comparatively cheap, but is by no means as 

 deadly as phosphorus or strychnine. The smallest quantity known to 

 have been fatal to a human being is 2.5 grains. Ordinarily 2 grains 

 would be a dangerous dose for an adult; but much larger quantities 

 are known to have been taken by persons who had become arsenic 

 eaters. Farriers often give a horse a dose of 20 grains without bad 

 results. Its action on rodents is exceedingly variable, and there is 

 ample proof that rats after taking small doses frequently become 

 entirely immune to its further effects. 



White arsenic is sparingly soluble in water, and the crystallized 

 form is less soluble than the amorphous. Both forms are acid to 

 test paper, and to some extent acidulate food with which they are 

 mixed. Experience seems to prove that the souring of baits is often 

 sufficient to keep rodents from eating them. This circumstance and 

 the uncertainty of results even when baits are eaten are the chief 

 objections to arsenic. As an alternative, when the bitterness of strych- 

 nine prevents baits from being eaten, arsenic is a useful poison. 



STRYCHNINE. 



Strychnine is one of four alkaloids obtained from nux vomica, the 

 seed of a tree known to botanists as Strychnos nux vomica. The chief 

 supply comes from the Malabar Coast, India. Strychnine occurs also 

 in the bark of the same tree, and probably in all plants of the genus 

 Strychnos. 



The strychnine of commerce consists of the alkaloid in colorless 

 crystals or white powder, and of several salts, chiefly the sulphate 

 and the nitrate, in needle-like crystals or powder. The alkaloid is 



