24 N. H. AGR. EXPERIMENT STATION. [Bulletin 183 



.POSSIBLE DANGER OF HUMAN POISONING. 



TOXIC STANDARDS. 



In standard works on toxicology will be found the approximate 

 amount of arsenic considered to be dangerous as well as the 

 amount commonly prescribed as a medicinal dose. The medic- 

 inal dose, expressed as arsenious oxid, AS2O3, is 2 milligrams, 

 with a maximum of 5 milligrams. The dangerous dose is com- 

 monly quoted as 60 milligrams and the minimum recorded fatal 

 dose is given as 130 milligrams. • 



The amount that may be administered in medicine is, of course, 

 fixed by long years of practice. As regards the danger of fatal 

 doses, however, some comments may be proposed. The amounts 

 quoted as dangerous or fatal are naturally based on many records, 

 partly from the annals of criminology. In these sundry cases 

 the form in which the arsenic has been ingested has varied. 

 In some instances it has been taken in a soluble form as in 

 Fowl er's solution. In others it has been in the form of common 

 white arsenic or arsenious oxid AS2O3. In this form its solubUity 

 varies, influenced in part by its physical condition. One part 

 may dissolve in 30 to 80 parts of water or may require as much 

 as 400 parts of water. 



If now, we attempt to draw a comparison between the possible 

 toxic properties of the arsenic in arsenate of lead and those of 

 arsenic as quoted in the literature of toxicology, we find ourselves 

 dealing with some unknown factors. Remembering that the 

 poisonous properties of a substance, aside from its corrosive 

 quaHties, are dependent on the extent to which it is dissolved 

 after being ingested, we should need to know something of the 

 solubility of arsenate of lead in human gastric juice, in order to 

 appraise its possible danger. This solubility, as noted further, 

 was determined for us by the Hull Physiological Laboratory of 

 Chicago University. 



In general, we may propose that the arsenic in arsenate of lead 

 is not going to prove more toxic than that in common white 

 arsenic, AS2O3. This is for the reason that arsenate of lead is 

 specifically devised to present arsenic in a form largely insoluble* 

 in order to avoid burning the foliage of plants that are sprayed; 

 and it accomplishes this purpose. Common white arsenic on 



