May 1, 1864.] THE TECHNOLOGIST. 



THE PATENT PLUMBAGO CRUCIBLE COMPANY. 469 



crucibles a factitious polish and smoothness generally followed by Con- 

 tinental makers is not adopted by the Company. 



From the kiln the goods are conveyed to the store-room, or to the 

 packing-room if they have to be shipped at once. The goods are nearly 

 always packed in old sugar hogsheads, which are strong, large, cheap, 

 and plentiful. Turning out on to the wharf we see thirty of these 

 hogsheads packed ready to be shipped for Vienna ; and lying alongside, 

 150 cases containing crucibles for the Italian Government. These 

 orders, not by any means unusual in magnitude, will enable our readers 

 to form an idea of the scale upon which the operations of the Company 

 are conducted. 



We now cross the yard to the workshops of the Clay department, 

 where various descriptions of crucibles are manufactured. The larger 

 sizes, as in the case of plumbago crucibles, are made at the potter's 

 wheel, but the smaller, in which the Company can successfully com- 

 pete with the best French makers, are fashioned by beating the clay 

 upon boxwood mandrils. The so-called "white-fluxing pots" are really 

 beautiful specimens of earthenware, and are acknowledged by the best 

 authorities on metallurgy to be very refractory, and to withstand the 

 action of fluxes in a most remarkable manner. Every pot is made by 

 gauge, and each moulder is consequently provided with a great number 

 of pattern ribs cut from boxwood and ebony. The little crucibles used 

 in assaying almost equal the German porcelain crucibles in thinness and 

 smoothness. The smallest are not much more than an inch high. Be- 

 sides crucibles, all kinds of clay instruments used in assaying are here 

 manufactured, such as scorifiers, roasting dishes, and muffles. The 

 convenient clay furnaces used by assayers, dentists, and experimental 

 chemists, are also made in great numbers. 



Let us now turn back to the store-rooms and look at a few of the 

 curiosities that are to be found there. We have just been speaking 

 of a crucible about an inch high. We notice one, of the pattern supplied 

 to the Koyal Mints, intended for melting 600 pounds' weight of silver. 

 Here again is another plumbago pot, made specially for zincing the 

 Armstrong shot, and which will hold 800 lbs. of molten zinc. The 

 medium-sized plumbago pots now so extensively employed for melting 

 silver, gold, copper, brass, and malleable iron, are, of course, the most 

 important products of the works. All the pots are numbered according 

 to their contents, each number standing for one kilogramme, or a little 

 over two pounds ; thus — a No. 2 crucible contains two kilogrammes ; a 

 No. 3, three kilogrammes, and so on. Covers, stands, and stirrers of 

 plumbago are kept in stock with every conceivable article of fire-clay, 

 from the huge glass pot down to the humble fire-ball for the parlour 

 grate. 



The graphite imported by the Company is not used solely in the 

 manufacture of melting-pots and metallurgical apparatus. A good pro- 

 portion of this valuable raw material is prepared for domestic purposes, 



