172 ELECTROLYSIS. 



This mixture gives some elasticity to the mould. 



III. Bismuth ..... 250 grammes. 



Lead .. .. 160 



Tin 125 



Antimony .. .. 30 



Mix, and melt in a clean crucible. 



IV. Bismuth 280 grammes. 



Lead .. .. 190 



Tin 100 



In order to obtain a good result from the two last formulae 

 the metals are first melted and poured in a vessel containing 

 cold water and a small quantity of straw and hay cut in lengths 

 of about 3 inches. The whole is thoroughly stirred whilst the 

 molten metal is being poured. This divides the metal into 

 shots, which are dried and melted again. 



V. Gelatine 500 grammes. 



Water 700 



Wax .. .. 15 



The gelatine is dissolved in water on a gentle fire and some 

 beeswax in small pieces is added. This mixture must be used 

 tepid and not hot. 



VI. Beeswax 9 kilogrammes. 



Venetian turpentine 1*35 



Plumbago in an impalpable state ' 225 



Care must be taken to avoid any dust. If during the cold 

 weather any crack occurs a little Venetian turpentine is added. 

 When the temperature is sufficiently high turpentine can be 

 dispensed with altogether. 



According to Mr. Urquhart, this last mixture is extensively 

 used in England. 



The wood engraving is first cleansed with a hard brush and 

 essence, then dried in sawdust, and sprinkled with extremely 

 fine plumbago. Some wax of good quality is then melted into 

 a copper pan and slowly stirred at the same time that the 

 plumbago is being poured in. The mixture must be thorough 

 and pasty, almost liquid. It is necessary to maintain it at a 

 certain temperature without boiling it, and to stir it well to 



