142 



SCIENTIFIC AMUSEMENTS. 



It should therefore be prepared in the open air, or in a stable or 

 outhouse, and not inside a dwelling-house, where, in addition to 

 causing annoyance on account of its frightful odour, it may do 

 other damage to paint and furniture. In laboratories where it is 

 extensively used, the apparatus is usually placed inside a " fume 



chamber " or " stink cupboard," i.e., 

 a kind of closet furnished with a flue 

 and a glass door in front (fig. 67) ; 

 by means of a gas jet or otherwise a 

 current of air is kept ascending the 

 flue, so that any evil-smelling sub- 

 stances or dangerous gases and 

 vapours can be manipulated inside 

 the cupboard, the door being closed 

 when the operator does not require 

 to touch the apparatus, so as to avoid 

 leakage of fumes and smells into the 

 apartment. 



The unpleasant smell of rotten 

 eggs is due to the fact that sul- 

 phuretted hydrogen is produced 



Fig. 67. Stink-Closet. 



during their putrefaction. The gas is also produced by certain 

 natural chemical actions taking place underground, so that the 

 water of springs in localities where this occurs dissolves the gas, 

 and acquires its disagreeable odour. Harrogate, in Yorkshire, is 

 one well-known place where " sulphur springs " of this kind 

 occur. In consequence of the property possessed by this gas 

 to form black compounds on coming in contact with certain 

 metallic compounds (Expt. 14), it discolours ordinary paint, 

 because white lead is an ingredient therein, and is a compound 

 acted upon in much the same fashion as silver or copper nitrate. 

 Certain kinds of powder used by ladies as cosmetics contain 

 lead, and others bismuth; in consequence, complexions that 

 have been improved (?) by the use of such cosmetics will not 

 stand the atmosphere of a sulphur spring, but turn grey, brown, 

 or even black on contact with air impregnated with sulphuretted 

 hydrogen. 



Expt. 146. To illustrate the Action of Sulphuretted Hydro- 

 gen on Paint. One white metallic compound used for paint, zinc 

 ivhite, is not affected by sulphuretted hydrogen. Procure a little 

 of this mixed with linseed oil ready for use, and with it paint one 

 side of the head of a plaster cast, or some similar object. Paint the 

 other side in the same way with ordinary white paint made from oil 

 and white lead. Now expose the painted cast to air containing sul- 



