128 THE BOOK OF THE LANTERN. 



nature, and such as can be found in most households. 

 Here is the list : An earthenware pot with a cover to it, 

 of about one pint capacity ; a glass tumbler ; a preserving- 

 pan or saucepan standing on a tripod, with a spirit-lamp 

 or Bunsen flame beneath it; a thermometer, two glass 

 stirring rods, a square of Berlin-work canvas, an earthen- 

 ware colander, and a dish. In the earthenware pot put 

 the following : 



Gelatine ... ... ... ... 110 grains. 



Potassic Bromide... ... ... 62 ,, 



(Ten per cent.) Solution of Salicylic Acid in Alcohol, \ ounce. 

 Water ... ... ... ... 2 ounces. 



I recommend the use of either Autotype, the Swiss, or 

 Henderson's make of gelatine. After being weighed it 

 should be cut up into strips with scissors and placed in the 

 jar with the other ingredients. With a glass rod press 

 down the gelatine into the water, so that every particle of 

 it is wet and softened. Set aside for ten minutes to swell. 

 Now half fill the preserving-pan with warm water, and 

 place the flame beneath it. The thermometer should be 

 placed in the pan, so as to check the temperature, which 

 should not be allowed to rise about 96 Fahr. Place the 

 pot containing the gelatine in the water, taking the precau- 

 tion to put a piece of thick paper beneath it, so that it 

 does not actually touch the heated bottom. 



The gelatine will very gradually melt, and the opera- 

 tion may be hastened by an occasional stir with the glass 

 rod. Even when it becomes quite limpid, little particles 

 of undissolved gelatine may be floating about in it 

 and these should disappear before proceeding further, or 



