38o BOOK IX. 



blow into the furnace in either a mild or a vigorous manner. For those ores 

 which heat and fuse easily, a low hearth is necessary for the work of the 

 smelters, and the pipe must be placed at a gentle angle to produce a mild 

 blast from the bellows. On the contrary, those ores that heat and fuse 

 slowly must have a high hearth, and the pipe must be placed at a steep incline 

 in order to blow a strong blast of the bellows, and it is necessary, for this 

 kind of ore, to have a very hot furnace in which slags, or cakes melted from 

 pyrites, or stones which melt easily in the fire^^, are first melted, so that the 

 ore should not settle in the hearth of the furnace and obstruct and choke up 

 the tap-hole, as the minute metaUic particles that have been washed from 

 the ores are wont to do. Large bellows have wide nozzles, for if they were 

 narrow the copious and strong blast would be too much compressed and too 

 acutely blown into the furnace, and then the melted material would be 

 chilled, and would form sows around the nozzle, and thus obstruct the opening 

 into the furnace, which would cause great damage to the proprietors' 

 property. If the ores agglomerate and do not fuse, the smelter, mounting 

 on the ladder placed against the side of the furnace, divides the charge with 

 a pointed or hooked bar, which he also pushes down into the pipe in 



^^" Stones which easily melt in the fire." Nowhere in De Re Metallica does the author 

 explain these substances. However in the Interpretatio (p. 465) he gives three genera or orders 

 with their German equivalents, as follows : — " Lapides qui igni liqiiesctmt primi generis, — 

 Schone fliisse ; secundi, — flusse ziim schmeltzen flock quertze ; tertii, — quertze oder kiselsiein." 

 We confess our inability to make certain of most of the substances comprised in the first and 

 second orders. We consider they were in part fluor-spar, and in any event the third order 

 embraced varieties of quartz, flint, and silicious material generally. As the matter is of 

 importance from a metallurgical point of view, we reproduce at some length Agricola's own 

 statements on the subject from Bermannus and De Natura Fossilium. In the latter (p. 268) 

 he states : " Finally there now remain those stones which I call ' stones which easily melt in 

 the fire,' because when thrown into hot furnaces they flow [fiimnt). There are three orders 

 (genera) of these. The first resembles the transparent gems ; the second is not similar, 

 and is generally not translucent ; it is translucent in some part, and in rare instances 

 altogether translucent. The first is sparingly found in silver and other mines ; the second 

 abounds in veins of its own. The third genus is the material from which glass is made, 

 although it can also be made out of the other two. The stones of the first order are not 

 only transparent, but are also resplendent, and have the colours of gems, for some resemble 

 crystal, others emerald, heliotrope, lapis lazuli, amethyst, sapphire, ruby, chrysolithus, morion 

 (cairngorm ?), and other gems, but they differ from them in hardness. ... To the 

 first genus belongs the lapis alahandicus (modern albandite ?). if indeed it was different 

 from the alabandic carbuncle. It can be melted, according to Pliny, in the fire, and fused 

 for the preparation of glass. It is black, but verging upon purple. It comes from 

 Caria, near Alabanda, and from Miletus in the same province. The second order of stones 

 does not show a great variety of colours, and seldom beautiful ones, for it is generally white, 

 whitish, grejnsh, or yellowish. Because these (stones) very readily melt in the fire, they are 

 added to the ores from which the metals are smelted. The small stones found in veins, 

 veinlets, and the spaces between the veins, of the highest peaks of the Sudetic range (Sudi- 

 torum montium), belong partly to this genus and partly to the first. They differ in size, 

 being large and small ; and in shape, some being round or angular or pointed ; in colour they 

 are black or ash-grey, or yellow, or purple, or violet, or iron colour. All of these are lacking 

 in metals. Neither do the little stones contain any metals which are usually found in the 

 streams where gold dust is collected by washing. ... In the rivers where are collected 

 the small stones from which tin is smelted, there are three genera of small stones to be found, 

 all somewhat rounded and of very light weight, and devoid of all metals. The largest are 

 black, both on the outside and inside, smooth and brilliant like a mirror ; the medium-sized 

 are either bluish black or ash-grey ; the smallest are of a yellowish colour, somewhat like a 

 silkworm. But because both the former and the latter stones are devoid of metals, and fly 

 to pieces under the blows of the hammer, we classify them as sand or gravel. Glass is made 

 from the stones of the third order, and particularly from sand. For when this is thrown 

 into the heated furnace it is melted by the fire. . . . This kind of stone is either found 



