352 Messrs. J. H. Priestley and R C. Knight. Toxic [Feb. 13, 



The following experiments show that solutions of about this strength of 

 acidity, and containing nothing but nitric and nitrous acids, are capable of 

 destroying the bacteria. A solution containing approximately 0"002 grm. 

 of nitric acid and - 003 grm. potassium nitrate per cubic centimetre was 

 made up and its acidity determined. From it were made solutions corre- 

 sponding respectively to 



No. Grammes of nitric acid 



per c.c. 



1 0-0007 



2 0-0003 



3 0-0005 



4 0-0003 



Each was then infected with the bacillus, well shaken, and after an hour 

 subcultures were made. All the plates proved sterile upon incubation, 

 indicating the failure of the organisms to exist in such solutions. Controls 

 with untreated distilled water were carried out simultaneously with the 

 above experiments, and plates infected from these showed luxurious growth. 

 „ Thornton, in his paper, intimates that the criticism had been made that 

 hydrogen peroxide might be responsible for the sterilising action of the 

 discharge, but on discharging on to a test solution of potassium titanium 

 sulphate, which detects minute quantities of hydrogen peroxide by the 

 formation of yellow titanium peroxide, we found that no measurable amount 

 of that compound was formed. Indeed, it seems unlikely that hydrogen 

 peroxide would exist in the presence of excess of ozone, the two tending to 

 interact with mutual reduction : — 



H 2 2 + 3 — H 2 + 20 2 . 

 2. Discharge in Hydrogen. — It is chiefly upon his experiments in hydrogen 

 that Thornton bases his conclusions as to the direct instrumentality of the 

 current in the bactericidal action. These experiments have therefore been 

 carefully repeated, using the same form of electrode by means of which 

 a continuous stream of hydrogen was caused to enter the discharge vessel 

 by sweeping past the discharging point. Pains were taken to obtain the 

 hydrogen in a comparatively pure state, since discharge in the unpurified 

 gas resulted in the formation of a film of metallic appearance, possibly 

 arsenic, on the object discharged upon. Therefore all hydrogen, after leaving 

 the cylinder containing it under pressure and before being used, was passed 

 slowly through three U -tubes containing respectively soda-lime, silver 

 nitrate crystals and lumps of a mixture of lime and mercuric chloride, and, 

 finally, through wash-bottles of strong sulphuric acid and potassium 

 pyrogallate solution. In the latter, solutions of caustic potash and pyrogallic 



