MECHANICS AND USEFUL ARTS. 97 



aniline, forming a mixture consisting of free chlorine and inter- 

 mediate oxygen acids of chlorine ; and the remainder unites with 

 this mixture, forming the black dye. 



NITKOGLYCEEINE. 



Nitroglycerine is the product of the reaction which ensues when 

 glycerine is slowly poured into a mixture of concentrated nitric 

 acid, Avith twice its bulk of oil of vitriol. The glycerine loses 

 three equivalents of water, which are replaced by three of nitric 

 acid. It has been called also trinitrine, triiiitro-glycerine, etc. 



It is a liquid of specific gravity 1.6, nearly insoluble in water, 

 easily soluble in alcohol and ether. It has great stability, and 

 keeps indefinitely ; foreign bodies do not favor its decomposition ; 

 at ordinary temperatures it even remains unchanged in presence 

 of phosphorus and jjotassium. It does not explode by flame ; 

 burns by contact with an ignited body, but ceases to burn as soon 

 as the contact is at an end. It explodes only at 860° Fahr. It 

 detonates by a violent blow of a hammer, but only the part sub- 

 mitted to the blow explodes, without action on the surrounding 

 liquid. Its principal advantages in blasting in mines are, 1st. 

 Being insoluble in water and heavier than it, it can be used in 

 wet mines and under water. 2d. Not exploding by contact of 

 an ignited body, unless strongly compressed, it may be carried, 

 kept, and handled without danger. 3d. Its expansive force 

 being ten times greater than gunpowder, it economizes labor. 

 4th. The rapidity of its exiilosion renders tamping of no im- 

 portance, and thus renders the miner perfectly safe. 5th. It is 

 as efficient in a soft and crumbling stone as in a hard and com- 

 pact one ; it leaves no residuum. — Annales dn Genie Civil. 



It is an oily fluid of a light yellow color, and of 1.6 specific 

 gravity. It consists of 3 atoms of nitric-acid, or 3 NO5, com- 

 bined with an atom of glycerine, C^ H^ O^, so that its ultimate 

 composition may be represented by C^ H^ Ois N. The changes 

 which occur during explosion convert each volume of it into 469 

 volumes of carbonic acid, 654 volumes of steam, 39 volumes of 

 oxygen, and 236 volumes of niti'ogen, being a total of 1,298 vol- 

 umes of gas for each volume of the liquid oil, being thus five 

 times more efi'ective than its bulk of gunpowder ; but from the 

 greater amount of heat generated, and the consequent higher 

 tension of the gases produced by the explosion, the new agent is 

 really thirteen times more effective, bulk for bulk, and eight times 

 more effective, weight for weight, than gunpowder, resulting, for 

 blasting puri^oses, in very great economy of labor. — London Me- 

 chanics'' Magazine, September, 1865. 



The explosive properties of nitroglycerine C^ H^ (N 0)i Os, and 

 the accounts of experiments made with it in dift'erent parts of 

 Sweden, Germany, and Switzerland, determined MM. Schmitt 

 and Dietsch, the proprietors of the great quarries of sandstone in 

 the valley of Zorn, Lower Rhine, to try to use it in their works. 



The trial proved so successful, l^oth as regards economy and 

 the ease and rapidity with which the work was performed, that, 

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