ETHEREAL OILS.. 323 



pungent smell, also plav a not unimportant part in the 

 perfume factor\-. Thev are used in the manufacture of 

 smelling-salts, and the odour of snuff is due principalh' 

 to Ammonia. Besides this snulfs are rendered aromatic 

 by other sweet -smelling constituents. Acetic acid, too. 

 is employed in the perfume factory, and its property of 

 dissolving ethereal oils is made use of to jjrepare per- 

 fumed vinegars. 



chapi;kr XI. 



Etliereal oils act as ]:ioison if the^- are taken intern- 

 allv in too large doses, or continualh'. Hence the harmful 

 results consequent upon the abuse of man\" liqueurs are 

 caused not onl\- by the alcoh(jl which the\ contain, but 

 also b-\' the volatile oils with which the\- are llavoured. 

 ?jau de C'olog^ne is ei_|Liidl\- dangerous it clrLuik. It is 

 not uncommon for a doctor t" disco\'er h\- accident that 

 a secret habit, on the part of his lad^■ patients, of drinking 

 Eau de Cologne, is the cause of puzzling svniptoms. 

 \'olatile oils take ox^-gen from the air and thus go through 

 a process of o.wdation. Ahuu' of these oils ()x\clise \er\' 

 quickh' and the more minuteh' the\' are dispersed in the 

 air tlie more rapid is the process. Light and damp 

 further this process, whiclr gi\'es rise to gase<ms ozone 

 in the air. or liquid h\'drogen superox\-de which is ver\- 

 similar in its effects. To these is to be ascribed the 

 stimulating effect on the respiratorA' organs which alco- 

 holic solutions of volatile oils have when evaporated in 

 a room. ^Fhis effect is produced especialh' when those 



