92 



CHEMISTRY. 



was almost quite clear; that from the artificial 

 product was much redder, and the supernatant 

 liquid was highly-colored ; the purpurine pre- 

 cipitate was of a purplish-red color. The 

 natural alizarine and purpurine precipitates 

 did not seem to be much affected by being 

 washed several times with cold water, but the 

 artificial alizarine precipitates gradually dis- 

 solved in the washing water, and finally disap- 

 peared. Mr. Young thoroughly tested the 

 dyeing powers of the new alizarine by com- 

 paring the results produced upon mordanted 

 cloth with equal weights of sublimed aliza- 

 rine obtained from the two artificial prep- 

 arations and from madder, and of purpurine ; 

 he showed the specimens of cloth so treated. 

 Instead of the dark, full red given by the natu- 

 ral substance, the artificial alizarine yielded 

 only a yellowish-red, much like that of the 

 purpurine. Its purple was of a slaty tint, but 

 the chocolate and black differed very slightly 

 from those of the natural alizarine. The pur- 

 purine scarcely gave any purple, and the same 

 is true of the Continental and English madder- 

 substitutes. Alcoholic solution of natural ali- 

 zarine gives a fine purple color with copper 

 acetate, and with the same reagent the artificial 

 preparation gives a very red purple. No char- 

 acteristic bands appear in the spectrum when 

 artificial alizarine is used, and, therefore, pur- 

 purine is shown to be totally absent. The 

 author was not aware if any thing had been 

 done toward establishing a formula for the new 

 alizarine, but his opinion, arrived at after per- 

 forming many practical experiments, was that 

 there was some essential difference between 

 the artificial and the natural substance. He 

 had found no superiority in the new substance. 

 In a supplement to the paper of which the fore- 

 going is an abstract, Mr. Young said that the 

 manufacture of artificial alizarine is carried out 

 in two or three ways by Continental chemists, 

 and, from the examination which has been made 

 of the products, it would appear that some of 

 them consist of a mixture of alizarine and pur- 

 purine, in different proportions, and some of 

 alizarine, or of a substance intermediate be- 

 tween the two. 



New Explosive Powders (see AMERICAN Ax- 

 NUAL CYCLOPEDIA for 1869). The new explo- 

 sive agent, popularly called picrate powder, 

 invented in France, and made under the pa- 

 tronage of Napoleon's government, has not yet, 

 so far as known, been employed in war, or to 

 any great extent in blasting. Its value and 

 comparative safety are still matters of doubt. 

 The Scientific Journal says of the new com- 

 pound: 



It is most readily prepared by the double decom- 

 position of a soluble picrate of soda, magnesia, or 

 lime, and a salt of potash, or by the direct action of 

 picric acid upon the carbonate of potassa. The ex- 

 plosion of the picrate gives rise to an immense vol- 

 ume of gaseous matter, as nitrogen, carbonic, and 

 hydrogen, and oxygen, and the only solid residuum 

 is a little carbon and carbonate of potassa. The 

 smoke produced is very light and easily dissipated, 



and the gaseous products are totally destitute of the 

 corrosive and poisonous action of those of gunpow- 

 der, with their thick, heavy, stifling smoke. Nearly 

 insoluble in cold water, there is no absorption of 

 moisture from the atmosphere to deteriorate its qual- 

 ity or destroy its utility, as with gunpowder, so that 

 it may be used in the dampest mines, where also the 

 almost total absence of smoke and of noxious prod- 

 ucts after explosion is a great recommendation. 



Two varieties of the picrate powder are now man- 

 ufactured, one for blasting, the other for fire-arms : 

 each made of various grades of strength, and adapted. 

 for special applications. For the first purpose, ni- 

 trate of potash is used with the picrate ; for the sec- 

 ond, an additional ingredient, charcoal, is employed, 

 the latter being added to diminish the rapidity of the 

 combustion and increase the projectile force. This 

 can be regulated so as to be greater or less than that 

 of gunpowder, while the blasting power is much 

 greater than that of the latter substance. 



Our space will not permit us to go into more detail 

 respecting this new powder, which is so easily made 

 and kept unchanged, and can be made of any desired 

 degree of strength, and in its explosion yields no 

 deleterious or corrosive gases, blinding smoke, or 

 acrid and troublesome residuum. It is nearly as 

 cheap as, and less easily ignited by carelessness or ac- 

 cident than, gunpowder. Of much greater blasting 

 power, and quite equal to nitro-glycerine in this re- 

 spect, it seems destined to play a very important part 

 in mining operations, while the comparative absence 

 of solid deposit renders its use in gunnery highly 

 advantageous. The color is a brilliant yellow, and 

 thus it it is easily distinguished among other sub- 

 stances. It is also of varied application in pyrotech- 

 nics. 



Mr. Percy A. Blake, of England, has pat- 

 ented a powder which he calls the " Safety 

 Explosive Compound." Its constituents are 

 simply sulphur and chlorate of potash, in the 

 proportions of one of the former to two of 

 the latter. These substances can be kept sep- 

 arately, in a dry powdered state, and mixed by 

 sifting when required. This mixture has been 

 known for years to detonate when struck with 

 a hammer, but was useless as an explosive 

 agent, because it merely burned slowly when 

 fired by the ordinary fuses. The invention, 

 therefore, consists in causing this compound 

 practically to explode by the use of a peculiar 

 kind of detonating tube, or percussion-cap, 

 which renders it exceedingly serviceable for 

 torpedoes, blasting, shells, blowing down pali- 

 sades, and other similar appliances. The de- 

 tonating tube to be employed is made of metal, 

 about an inch in length, and about -% of an 

 inch in diameter, the bore being about ^ ; but 

 the inventor does not confine himself exactly 

 to these dimensions, as a larger or smaller tube 

 can be used for the purpose. First is intro- 

 duced into it some of the compound, and well 

 pressed down; next, some fulminating mer- 

 cury, and then a small quantity of detonating 

 silver, and the rest of the tube may be filled 

 up with meal powder. The end of the tube, 

 which is filled with the compound, is to be 

 placed in contact with the compound con- 

 tained in the vessel to be fired, and the other 

 end may be fired by any kind of ignition ap- 

 paratus. 



M. Nobel, a Prussian engineer, has patented 

 two new varieties of powder, composed as fol- 



