470 Imitation of Dama/cus Steel.— Tejl ef Uniformity in Steel. 



mixed with oil, and wrapped in a paper, which had before been "rolled upon the phig, and 

 confcqucntly fitted the cylinder. The ends of the paper were neatly folded ; and the whole 

 mafs being then put into the cad-iron cylinder placed upon the anvil, a few blows were 

 given by driving the plug into the hole with a heavy hanin)er. By this means the mafs of 

 filings, when thruft out of the cylinder, was compact and manageable. Ic w;'.s then placed 

 in a charcoal fire, and urged to a welding heat by the double bellows. Thence it was taken 

 with the tongs ; again hallily put into the cylinder, and hammered by means of the plug 

 and the heavy hammer. When it was taken out, the whole was found to be confolidatcd ; 

 but upon forging it into a plate, a confiderable portion flew off in a crumbly form. The 

 plate, however, was filed up, fmoothed, and examined. 



Its colour prcfented nothing remarkable. When weak nitrous acid was poured upon it, it 

 became mottled in confequence of the numerous fmall black fpots which appeared upon the 

 particles of fleel, while thofc of iron remained clean. On the nitrous acid being waflied off, 

 the furface appeared wavy like the Damafcus fteel, but fcarcely at all fibrous ; doubtlcfs be- 

 caufc the folid had not been drawn out by forging. An attempt was made to harden it by 

 ignition and cooling in water ; but it ftill remained foft enough to be cut with the graving 

 tool, the point of which did not indicate any difference in that refpe£l between tJie parts of 

 iron and of fleel, though it is very probable fuch a difference did really exill. 



I infer, therefore, that the Damafcus fteel is in faift a mechanical mixture of fteel and 

 iron; that it is incapable of any confiderable degree of hardnefs, and confequently is in 

 no danger of breaking from its brittlencfs ; that its tenacity is enfured not only from the 

 admixture of iron, but likewife from the facility with which its foundnefs may be afcer- 

 tained throughout, by the fame procefs which exhibits the water or fibrous appearance: 

 and, laftly, that the edge of a weapon formed of tliis material muft be rough, on account 

 of the different refiftance which the two fubRances afford to the grindflone, in confcquenca 

 of which it will operate as a faw, and more readily cut through yielding fubftances than 

 fuch cutting tools as are formed of a more uniform fubffance. 



This experimental enquiry direfted my attention to a method of afcertaining the uni- 

 formity of texture in iron or fteel, which perhaps may have been noticed by others, but 

 is certainly unknown in moft manufaiflorles, though I have found it of great utility. If a 

 weak acid, for example the nitrous, which I have ufually taken in a very diluted ftate, be 

 applied to the face of iron or fteel previoufly cleaned with the file, or with emery paper, 

 the parts which contain the greateft portion of carbuixt of iron (or plumbago) immedi- 

 ately fhew themfelves by their dark colour. It very frequently happens that articles of con- 

 fiderable value, intended to be fabricated in iron or fteel, are not known to be defeiftive 

 until much expcnce has been laid out in manufacluring them. A piece of iron, which has 

 a vein of fteel running through it, as is too often the cafe, will require at leaft three times 

 the labour and care to turn it in the lathe, which would have been demanded by a piece 

 of greater uniformity. Steel which abounds with fpots, or veins, or fpecks called pins, 

 may be fafhioned completely, and will not fhew its defects, until tlie final operation when 

 the attempt is made to polifh it. Other articles, fuch as meafuring fcrews, bl.ides of ftieers, 

 fine circular cutters, &c. either bend in the hardening, from the difference of expanfion, 

 or refift the tool when wrought in the tempered ftate, or exhibit other incur.ible defcifls 

 when they come to be tried ■, which the left, by nilrou; acid would have indicated before 



any 



