NATURE OF HYDROCYANIC ACID. 



Hydrocyanic or Prussic acid (H CN or H Cy) is one of the most 

 energetic of poisons ; all animal life succumbs to it. It smells like 

 the oil of bitter almonds, and may be obtained by distillation from 

 the kernels of bitter almonds and of many other stone-fruits. 

 Enough is said to be contained in one and a half ounces of peack 

 kernels to kill a man. It is extremely volatile, and hence is more 

 generally known in the gaseous than in the liquid state. The gas is 

 lighter than air, and hence rapidly diffuses when generated under a 

 tent. Water dissolves it, and for this reason fumigation is apt to be 

 a failure when the trees are wet. 



Animals fatally poisoned with hydrocyanic acid gas survive for a 

 longer or shorter period according to the dose; death may take place 

 as early as the second minute and as late as the forty-fifth. The chances 

 are favourable for recovery when the poison is not fatal within an hour. 

 The nervous system is most affected ; death in man is said to be due 

 to paralysis of the heart- in the most rapid cases, and to paralysis of 

 the respiratory organs in those which are less quickly fatal. 

 Difficulty in breathing, pains in the head, giddiness, nausea, slowing 

 of the pulse, loss of muscular power, convulsions with expulsion erf 

 excretions, dilation of the pupils and protrusion of the eyes, and, 

 finally, cessation of the pulse and breathing are given as the 

 progressive symptoms. Chlorine and ammonia are valuable as 

 antidotes, but should be administered only by medical men. Cold 

 water dashed on the face, neck and over' the spine is valuable as a 

 remedy, and respiration should be kept up artificially. One or two 

 employes of the Horticultural Board, after working several 

 consecutive hours with the gas, have felt a slight swimming sensation 

 on nights when little air was stirring, and the writer has felc 

 -considerable nausea and giddiness as the result of recklessly 

 venturing into the Dock fumigation chamber before this had been 

 properly ventilated after the fumigation of fruit. No cases of fatal 

 or serious poisoning are known to have anywhere occurred to 

 operators of fumigation outfits, but the deadly nature of the gas has 

 often been impressed upon operators by the untimely end of small 

 animals and fowls which have been unintentionally enclosed with the 

 tree. 



The poisonous action of potassium cyanide is nearly identical with 

 that of hydrocyanic acid ; 2J grains or about 1/175 of an ounce is 

 regarded as a probable fatal dose for man. As this weight would 

 hardly suffice for a taste to an inquisitive person ignorant of the 

 nature of the substance, the necessity of keeping the containing 

 vessels plainly labelled " Deadly Poison " and under lock and key 

 when not being used is apparent to everyone. There is nothing in the 

 appearance of potassium cyanide to indicate its nature. The form 

 used for fumigation purposes bears a superficial resemblance to white 



