CHAPTEE XVII. 

 MERCURIC CHLORIDE (CORROSIVE SUBLIMATE)— TIN CRYSTALS. 



1 08. Mercuric Chloride (Corrosive Sublimate), HgCl,. — Pre= 

 paration. — By [dry] heating an intimate mixture of equal parts of 

 mercuric sulphate and common salt to which a little manganese 

 dioxide has been added. 



Properties. — White crystalline powder of which 6*57 grammes are 

 soluble in 100 grammes of water at 10° C, and 53-96 grammes in 100 

 gi'ammes of water at 100° C. It is slightly soluble in alcohol and very 

 soluble in ether, which exti'acts it even from its aqueous solutions. 

 The taste of corrosive sublimate is bitter and nauseous. It is a violent 

 poison, which absorbed by the mouth produces considerable inflamma- 

 tion of the mucous membrane, even to the point of destroying it. 

 Corrosive sublimate possesses the property of precipitating albumen ; 

 it forms with it mercuric compounds soluble in an excess of albumen 

 and in solutions of common salt. Its powerful antiseptic action results 

 from this affinity for albumen. Corrosive sublimate preparations should 

 be made in glass or earthenware dishes, the metals decomposing it. 



Action of Corrosive Sublimate on Plants. — Mercuric chloride 

 acts on plants like blue and green vitriols, but proportionately with 

 greater intensity. If the plant is placed through the roots in contact 

 with a certain dose of corrosive sublimate, it dies. Mouillefert found 

 that this dose for vines planted in 3-litre pots was 2 grammes in 250 

 cubic centimetres of water ; the dose of 0*5 gramme in 250 cubic 

 centimetres of water had no effect on the vine but killed weeds, chiefly 

 Mercurialis annua, Senecio vulgaris, So7ichus oleratus, Borrago offici- 

 nalis, Sinapis arvensis, Malva sylvestris, and Amarantus blitum. 

 Trials by Mouillefert to overcome the phylloxera show that coiTOsive 

 sublimate solutions are absorbed by the roots and poison the juice. 

 Spraying with corrosive sublimate solutions burns the leaves ; how- 

 ever, a solution of 0-015 per cent does not injure orange-tree leaves 

 (Coquillet). Mercurial sprayings are deadly to the vine (Leon Vignon 

 and J. Perraud). Dr. Cazeneuve's trials, however, tend to show that 

 corrosive sublimate used in 0-04-0-05 per cent does not hinder the 

 gi'owth of the vine. Like green and blue vitriols an infinitesimal 

 dose of sublimate may stimulate vegetation instead of injuring it. 

 Ono has shown that this dose is 0-0013 per cent for green algae pos- 

 sessing chlorophyll. The pickling of the seed in a 1-2 per cent bath 

 of corrosive sublimate does not diminish their germinative power. 

 Sturgis found that the seeds of the cotton plant germinate after steeping 

 half an hour in a 1-2 per cent solution of sublimate. 



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