118 PLINY'S NATURAL HISTORY. [Book XXXIII. 



ceived from the name, it is in reality the scum of a substance 

 in a state of fusion of the future metal, in fact. It differs 

 from scoria in the same way that the scum of a liquid differs 

 from the lees, the one 13 being an excretion thrown out 1>y~ 

 the metal while purifying itself, the other 4 * an excretion of 

 the metal when purified. 



Some persons distinguish two kinds of scum of silver, and 

 give them the names of " scirerytis" and " peumene ;" 45 u third 

 variety being molybdsena, of which we shall have to make 

 further mention when treating of lead.** To make this HCUIII 

 lit for use, the cakes are again broken into pieces the si/o 

 of a hazel-nut, and then melted, the lire being briskly blown 

 with the bellows. For the purpose of separating the charcoal 

 and ashes from it, it is then rinsed with vinegar or with wine, 

 and is so quenched. In the case of argyritis, it is recom- 

 mended, in order to blanch it, to break it into pieces the size 

 of a bean, and then to boil it with water in an earthen vessel, 

 iirst putting with it, wrapped in linen cloths, some new wheat 

 and barley, which are left there till they have lost the outer 

 coat. This done, they bruise the whole in mortars for six con- 

 secutive days, taking care to rinse the mixture in cold water 

 three times a da}', and after that, in an infusion of hot 

 water and fossil salt, one obolus of the latter to every pound 

 of scum : at the end of the six days it is put away for keep- 

 ing in a vessel of lead. 



Some persons boil it with white beans and a ptisan 47 of 

 barley, and then dry it in the sun ; others, again, with white 

 wool and beans, till such time as it imparts no darkness to the 

 wool ; after which, first adding fossil 18 salt, they change the 

 water from time to time, and then dry it (luring the forty hot- 

 test days of summer. In some instances the practice is, to 

 boil it in water in a Bwine's paunch, and then to take it out 

 and rub it with nitre ; after which, following the preceding 

 method, they pound it in a mortar with salt. Some again 



43 The litharge. 4i The scoria. 



i5 Nothing whatever is known ns to the identity of these varieties of 

 litharge. Indeed the words themselves are spelt in various "ways in the 

 respeetive MSS. 



* 6 In B. xxxiv. c. 53, where he identifies it with " galena,*' mentioned 

 in Chapter 31 of this Book. 



*' See I!, xviii. c. 13, B. xxi. c. 61, and B. xxii. c. GG. 



** Sal gem, or common salt. 



