504 SCIENTIFIC RECORD I-OR 188-1. 



amount of tbe soluble gnu-cottoii. Tlic jcllv is very insensitive to blows, 

 and is not easily exploded, requiriuj^- a very powerful fuse, and is not 

 iujured by water. It is said to be 75 ])er cent, stronger than dynamite, 

 and it is very free from liability to accident or injury in use or trans- 

 portation. On tbe other hand, its stability is questioned. General Abbot 

 found that samples underwent spontaneous decomposition, separating 

 into cellulose and free nitro-glycerine, with a copious evolution of nitrous 

 fumes. 



Sir Frederick Abel, chief of the chemical bureau of tbe Woolwich 

 Arsenal, had a miraculous escape from death early in Marcb, 1884. 

 He was barely ninety feet from tbe place where 1,000 kilograms of gun- 

 cotton accidentally exploded with terrific violence; he was knocked 

 down by the concussion and injured in several ])lacesby Hying missiles, 

 but in no wise dangerously. Sir Frederick ascribes his wonderful esca])e 

 to the fact that a strong wind was blowing at the time from him to- 

 wards the scene of tbe explosion. {Munroe's Notes on the Literature of 

 Explosives, No. VI.) 



Touffheninf/ Gold and Silver in the Crucible. — Dr. James C. Booth, of 

 tbe United States mint, Pbiladelpbia, describes a general method of 

 refining gold iii tbe crucible as practiced in tbe mint. Some britlle 

 gold, having been accidentally melted with a quantity of well-retined 

 and tough gold, was found to have rendered the whole mass very brittle, 

 with a highly crystalline fracture, and therefore useless for coinage. To 

 avoid loss of time and greater cost of refining by acid, it was tougbened 

 wholly by fluxing. This was accomplished on 75,162.55 ounces (5,154 

 l^ounds avoirdu})ois) in one and a half days, at a trifling cost, and with 

 scarcely apparent loss. Tbe 75,000 ounces were divided into fourteen 

 melts of about 5,400 ounces each, and each melt was separately tougb- 

 ieued. Tbe ingots, easily broken into pieces by striking them on tlie edge 

 of a wooden box, were put into tbe crucible with soda ash and anbydrous 

 fused borax, in the ratio of 1 or 2 ounces to a melt, until tbe crucible 

 was nearly full. It then appeared as a quiet mass of metal covered 

 with a rather viscid slag, disposed to swell and ])uli'. A few crystals of 

 saltpeter, say 1 or 2 ounces, were then dropped successively into tbe 

 center of the metallic surface, and, as they melted, their spreading out 

 over the whole surface was aided by tbe concentric motion of tbe bot- 

 tom of a small crucible. The moment tbe visible oxidizing action began 

 to slacken the melter skimmed oft" by a small black-lead dipping cruci- 

 ble tbe fluxed matter, as rapidly as was consistent with tbe care neces- 

 sary to avoid taking up metal. Tbe remainder in the melting-pot 

 was the tougbened metal. Tbe points to be noted are (1) that one 

 part of foreign matter sufficed to impart brittleness to 75,000 parts of 

 good standard gold ; (2) by a slight oxidizing ])roce8S the matter cimsing 

 brittlen^^ss was removed with no ap])reciable loss of gold ; (3) moreover, 

 the ratio of copper remained constant after tbe fluxing; (4) tbe tough- 



