CHEMISTRY. 



109 



on iodoret of starch, or on iodine itself. Ac- 

 cording to the author, the second process is 

 the best, and this is the one from which he 

 developed the three iodo-sulphates of soda, 

 potash, and ammonia. Each of these salts is 

 soluble in water, but very slightly in alcohol ; 

 the first and third are partly effervescent; 

 they are, besides, decomposable by heat and 

 by light, direct and indirect. 



Spontaneous Explosive. The Scientific Amer- 

 ican says that some experiments, recently 

 conducted at the Philadelphia High School, 

 demonstrated that when a strong solution of 

 phosphorus in bisulphide of carbon is poured 

 upon finely-powdered chlorate of potash rest- 

 ing on paper, and that mixture is exposed to 

 air, upon the evaporation of the bisulphides, 

 the phosphorus, being left in a finely-divided 

 state, intimately mixed with the chlorate, the 

 mixture presently explodes spontaneously, 

 with a loud report. The explosion is analo- 

 gous to that of phosphorus and chlorate of 

 potash when struck or rubbed together, the 

 mixture in the case cited being, however, 

 much more perfect than can be obtained by 

 any mechanical means. 



Dynamite. This explosive (which is a 

 combination of silica with nitre-glycerine 

 the former making the nitro-glycerine safer 

 for handling) has been tested by comparison 

 with other powders by the Austrian Govern- 

 ment. The report sums up as follows : 



1. The preparation of nitro-glycerine, and the 

 explosive mixtures of which it forms a part, partic- 

 ularly dynamite, is simple, safe, rapid, and gives a 

 uniform product. 2. These preparations can be ren- 

 dered safer for transportation and keeping than 

 gunpowder. 3. The loss from decomposition is less 

 than the deterioration of gunpowder by pulveriza- 

 tion and dampness. 4. For equal weights, dynamite 

 has from two to ten times the strength of gun- 

 powder; for equal volumes, four to sixteen times. 

 In the use of dynamite, 20 to 40 per cent, of expense 

 aad 40 to 70 per cent, of time are saved. For equal 

 weights dynamite removes 5 to 6 times as much 

 rock as powder, for equal volumes 8 to 10 times. 

 5. In water or rock impregnated with water, 50 per 

 cent, of expense and 100 per cent, of time are saved 

 by the use of dynamite. 6. The gases resulting from 

 the explosion of dynamite are much less noxious 

 than those from that of gunpowder. 



A comparison of dynamite and gun-cotton gives 

 the following results: 1. For equal volumes, gun- 

 cotton is less powerful than dynamite by 30-40 per 

 cent. 2. Gun-cotton costs 20-30 per cent, more than 

 dynamite. 3. Gun-cotton, for marine blasting, has 

 all the disadvantages of gunpowder. 4. The gases 

 from the explosion of dynamite are less noxious 

 than those from the explosion of gun-cotton. 5. 

 Gun-cotton is more sensitive to heat and mechanical 

 derangements than dynamite. Dynamite is also 

 easier of preparation. 



The disadvantages of dynamite are : 1. The easy 

 separation of nitro-glycerine from the silica by 

 water, in case the cartridges, permeable to water, are 

 left for some time submerged. 2. Becoming hard 

 at a temperature which causes difficulty in working 

 and using it. 



Lit7iofracteur.This (Anglice) " stone-break- 

 er " is a patented invention of Prof. Engels, of 

 Cologne. Lithofracteur is a new explosive com- 

 posed of nitro-glycerine as a base, and gun- 



cotton, the constituents of gunpowder, some 

 chlorates, and an infusorial earth. The sub- 

 stances are blended in a special way, and the 

 details of the manufacture are kept secret by 

 those concerned in it. The product is a black 

 compound of the consistence of soft putty, and 

 is made up for use into paper cartridges 4$- in. 

 long by |- of an inch in diameter, and weighing 

 If oz. each. When lighted in the air by or- 

 dinary means it simply burns out, leaving a 

 light white powder as a residuum ; but, when 

 it is ignited either in the air or in a closed 

 chamber with a capped fuse, its full violence 

 is developed. It is safe under all ordinary and 

 even extraordinary circumstances of storage 

 and transit, as recent experiments in England 

 and lengthened use on the Continent have 

 proved. It was used by the Prussians against 

 the French during the recent war, Herr En- 

 gels being the operator. After Fort Issy was 

 taken, the Prussians destroyed a number of 

 French heavy siege-guns by blowing off their 

 muzzles with lithofracteur. 



A long series of experiments was recently 

 conducted in England to test the value of the 

 compound. The following are given as some 

 of the results : 



The preliminary experiment consisted in throw- 

 ing a box containing 5 Ibs. of lithofracteur from the 

 top of the quarries, at a height of 150 feet from the 

 ground, into the plateau oelow. The box was 

 smashed and the cartridges were scattered about, 

 but not one was exploded. A cartridge was then 

 lighted by an ordinary fusee, when it burned slowly 

 out. Another cartridge was then placed upon a 

 block of stone and tired with a percussion fuse, 

 when a violent report followed, and the top face of 

 the stone was broken off. The power of the litho- 

 fracteur when confined was then exhibited by firing 

 charges in the bore-holes of several blocks of stone, 

 which were shattered into many fragments. The 

 tamping in all cases was effected with water, thus 

 proving the usefulness and reliableness of the com- 

 pound in workings where wet ground was met with. 

 The next part of the programme consisted in firing 

 a number of shots, both horizontal and vertical, in 

 the face of the quarry. As these were more or less 

 repetitions of each other, we need only notice a few 

 of them, although they all give extraordinary re- 

 sults. The holes were mostly bored under the 

 direction of some of the mining gentlemen present, 

 who, with a view of testing the compound to the 

 utmost, selected the worst possible spots, some of 

 which, they stated, gunpowder would not possibly 

 touch. The first of these blasts was made with a 1 

 Ib. 11 oz. of lithofracteur placed in a horizontal bore- 

 hole 3 ft. 4 in. deep, and li in. in diameter. A large 

 quantity of the stone was blown out to the front, and 

 the face of the rock was scaled and cracked over an 

 area of 20 ft. 6 in. wide by 13 ft. high. A couple 

 more shots were then fired simultaneously near to 

 the last, the bore-holes were each 3 ft. deep, and 

 were charged witli 13s oz. and 1 Ib. 1 oz. respectively, 

 and an immense face of rock was brought down. The 

 best blast, however, was the last of this series ; it 

 was fired in a vertical bore-hole, 4 ft. 6 in. deep, on 

 a ledge of rock, about 23 ft. from the level of the 

 plateau below, 1 Ib. 11 oz. of lithofracteur being 

 used. The explosion brought down at least 20 tons 

 of rock, and loosened an enormous mass behind the 

 bore-hole, the shot being one of the finest we ever 

 saw with so small a quantity of material. Some ex- 

 periments were next made with the view of showing 

 the disruptive effect of lithofracteur on iron, and for 



