648 PHILOSOPHICAL TRANSACTIONS. [aNNO 1734. 



the oily substance entirely consumed, and the matter in the crucible strongly 

 fired; afterwards boiling it in water, and washing it well, he obtained a black 

 sand, which was all endued with a vigorous attracting force. Pleased with this 

 success, he had a mind to try whether he could excite a greater force in it; he 

 therefore again roasted it with black soap as before, and even a third time: but 

 no addition was thus made to its virtue. He found that keeping it too long in 

 the lire is as prejudicial as keeping it too short a time; between half an hour 

 and an hour seemed to him the most proper space of time. 



He afterwards added to the black soap half the quantity of salt of tartar, 

 mixing it with an equal quantity of sand; which, when exposed in a crucible to 

 a reverberatory fire for ^ of an hour, he washed in water; and then so consi- 

 derable was the virtue of the sand, that if it did not exceed the former, it was 

 at least equal to it. 



And because he had observed the oiliness of the soap to conduce much to ex- 

 cite the virtue in the sand, he mixed beef-tallow with an equal quantity of 

 sand, and having closed the crucible very well, he exposed the whole mass to a 

 reverberatory fire for 2 hours; by which the sand became much blacker, and 

 received a great deal of attractive virtue; but that sand, which was burned 2 

 hours with an equal quantity of pitch, became more active, as also very black, 

 subtile, and very little shining; but when it was exposed a longer time in the 

 same crucible, he observed it to be weaker; as also when it was in the crucible 

 with the pitch but i- of an hour, it scarcely acquired any virtue; so that there 

 must be a determined action of fire to raise the virtue in the sand. Yet he 

 could not excite a greater virtue in the sand than by the following means, viz. 

 mixing the sand in the crucible with equal parts of rosin, pitch, frankincense, 

 and rape-oil, and exposing it to a reverberatory fire for an hour, having first 

 closed up the crucible well. Between the black coals of the oily matter, there 

 adheres a very black sand, which leaps up swiftly to the loadstone, as soon as 

 it is brought near it. He then considered whether the sand did not acquire the 

 greatest force, as it came nearer to the nature of steel, by burning it with the 

 abovementioned bodies; and in order to try this, he put it among such bodies 

 as turn iron into steel, according to the operations described by M. Reaumur, 

 in that excellent book. The Art of turning Iron into Steel. He therefore took 

 3 parts of sand, 2 parts of chimney soot, and of sea salt, powdered charcoal, 

 and ashes, one part each; having accurately mixed all these bodies together, 

 they were exposed for 6 hours in a close crucible to a strong fire; the whole 

 mass was then boiled and washed in water; then dried, and so received a great 

 deal of attracting force ; but it was not near so active as that prepared with soap, 

 or in the manner last described. 



