402 Alfred J. Ewart: 



beneath or between breathing pores to a depth of 3 to 4 milli- 

 metres. About the same effect was produced by placing apples 

 six inches away from 40 milligrams of iodine for two days, but 

 the spots appeared much sooner. 



In the case of other volatile substances such as prussic acid, 

 the diffusion is so rapid that the poisoning of the pulp takes 

 place generally unless the correct time of exposure is found to 

 produce pits. Thus one and two days' exposure to diluted 

 hydrocyanic acid killed the pulp throughout. After six hours' 

 exposure irregular brown areas of pulp appeared beneath the 

 skin, some becoming sunken and pit-like, and a few brown 

 patches radiated from the centre, unconnected with the surface. 



Chloroform. — Normal Jonathan apples kept in a 1 per lOOO 

 solution for three days, developed numerous large and small 

 spots and pits, and in many cases a white " efflorescence " 

 appeared on the skin, due to the partial solution of the bloom. 

 In 1 per 100,000 even after one week no pits or spots were 

 found, although a faint smell of chloroform was perceptible on 

 opening the cylinder. 



Prepared Jonathan Apples. — Examined after two weeks in air. 



One per 1000 (three days). Large, deep pits, with typical 

 brown, spongy, shrivelled bitter pit cells. 



One per 10,000 (one week). Pits 2-5 mm. deep. 



One per 100,000 (one week). Pits 1-3 mm. deep. 



One per 1,000,000 (one week). No perceptible signs of poi- 

 soning. 



Arseniuretted Hydrogen. — Whenever arsenic compounds are 

 in contact with organic matter, and particularly in the presence 

 of certain fungi, there is a possibility of the evolution of arseniu- 

 retted hydrogen gas. The conditions for the development of 

 minute traces of arseniuretted hydrogen gas, are present in any 

 orchard heavily sprayed with arsenical compounds, particularly 

 during close, moist weather. 



Normal Jonathan apples were exposed each in a 1500 cc. gas 

 cylinder to the arseniuretted hydrogen from 1 gram As-^Og, 

 and after keeping in air two weeks to allow all free gas to 

 escape, forwarded for analysis^. 



1 During Mr. Wilkinson's absence these tests wtre performed by Mr. Willgerodt, usinfr 

 the very delicate Giitzeit test for arsenic. 



