SALTS OF MERCURY 765 



formation of substances of the group known as chlor- 

 amines, thus : 



HC10 = NCl + H 2 

 R 2 / 



This = NCI group is strongly antiseptic. 



The Chloramines themselves have therefore been intro- 

 duced as antiseptics. The best known is Chloramine-T, 

 which is Benzene-sodium-sulphochloramide (C 6 H 5 .S(V 

 NaNCl). 



Other inorganic substances. Solutions of salts of mer- 

 cury exercise a powerful disinfectant action in proportion 

 to the amount of dissolved metal which they contain. 

 The most commonly used is the perchloride (corrosive 

 sublimate). Apart from its extremely poisonous char- 

 acter, it has the disadvantage of forming with albuminoid 

 substances both insoluble and soluble compounds of little 

 or no germicidal value, sulphuretted hydrogen converts it 

 into the insoluble and inert sulphide, and it acts on some 

 metals. The addition of acids or salts (e.g. hydrochloric 

 or tartaric acid or sodium or ammonium chloride) pre- 

 vents or largely reduces the formation of insoluble com- 

 pounds ; but it does not prevent the reactions resulting in 

 soluble substances, it may reduce the germicidal power 

 and the action of perchloride in the presence of albumin- 

 oids is therefore very variable. The reduction in germi- 

 cidal power by addition of sodium chloride is well seen 

 from the following results (Finlay, loc. cit.) : 



Number of colonies 

 16 litres of solution contained. developing after treat- 



ment for six minutes. 



mole HgCl 2 ..... 8 



HgCl 2 + 1 mole NaCl . . 32 



HgCl 2 + 2 moles NaCl . .124 



HgCl 2 + 4 NaCl . . 382 



HgCl 2 + 10 NaCl . . 1,087 



