MERCURIC CHLORIDE (CORROSIVE SUBLIMATE). 291 



Action of Corrosive Sublimate on Insects. — Contact with 

 corrosive sublimat:', even prolonged, has no action on insects and their 

 eggs ; thus the eggs of Bombi/x mori still hatch after twenty-four hours 

 steeping in a 1 per cent sohition. Sublimate is, however, a violent 

 poison ; it may enter with the food of the insect into their digestive 

 system. 



Use. — Lichens.— Wsbite obtained a negative result with a 1 per cent 

 solution. 



Potato Scab, produced by a bacteria, Bolley; Potato Pox (Ehizoc- 

 tinia Solani), Kuhn ; Bot of the Stem of the Potato (Ehizoctinia), 

 Eolfs.— Bolley found that corrosive sublimate is one of the best sub- 

 stances to disinfect seed potatoes and safely destroy all the bacteria and 

 spores of parasitic fungi on the surface of these tubers. The results 

 obtained controlled by Sturgis, Eolfs, and Woods were excellent. This 

 method, in fact gave 99 per cent of healthy potatoes, whilst the infected 

 potatoes (the untreated) only gave 1-4 per cent, and the tubers treated 

 by bouillie bordelaise, 53-57 per cent. But the effect of this treatment, 

 like that of the others already described, is 7iil if the potatoes are 

 planted in a field already infected and manured with infected dung. 

 The soil should be disinfected previously, or laid down to a different 

 crop for several years. Potatoes are disinfected thus : They are freed 

 from earth and the pellicular membranes surrounding them, then 

 steeped for 1| hours in a 3 per cent solution of corrosive sublimate. 

 They ai^e then washed, dried for a day, and then planted. Eolfs uses 

 a 0-94 per cent solution. Jones and Moi'se advise disinfection by im- 

 mersion for one hour in a 1 per cent steep of corrosive sublimate. Ger- 

 mination is normal even after steeping five hours ; after twenty-four 

 hours a certain injury occurs to the germinative capacity. 



Bacillus tabificans, Dell. — Bacillus which invades the leaves of the 

 beet and produces jaundice. Delacroix found this bacillus on the seed 

 and obtained sure disinfection by steeping the seeds in a 2 per cent 

 solution of sublimate. 



PeronosjMva viticola, De By. (mildew of (he vine). — Corrosive sub- 

 limate is, without doubt, a powerful anticryptogamic, which, in the 

 struggle against cryptogamie diseases of the vine, in general, might be 

 of great service if it were not so poisonous, and if it adhered better. 

 Cazeneuve in his trials with a mixture of excelsior verdigris 1 per cent, 

 and of corrosive sublimate 004 per cent, and with a solution of 

 mercuric chloride of 0'05 per cent, did not show in the first case any 

 greater categoric action than verdigris alone, but in the second case the 

 action was perfect. On the other hand, Kaserer obtained a perfect 

 result by the use of a solution containing 0"l-0'2 per csnt of sublimate 

 and milk of lime. The adherence of the sublimate being very bad, it 

 is necessary to multiply the treatments according to the frequency of 

 the rains if efficient protection of the plant be desired. An addition 

 of 0-5 per cent of starch has been tried to increase the adherence of 

 sublimate solutions. Corrosive sublimate is a very dangerous substance 

 to man, and there is no doubt that it can eventually pass, although in 

 small amount, from the grapes into the vine. Leon Vignon and J. 

 Perraud have estimated the mercury in drawn wine, pressed wane, lees 



