106 



POPULAR SCIENCE NEWS. 



[Jui.v, 1889. 



tix-iiibling to that dreaded hour when the 

 day-break gun shall banish sleep, not to 

 return until long past midnight. To many, 

 the Fourth of July has been the last straw 

 that broke the camel's back, and carried 

 exhaustion to that point where recovery be- 

 came impossible, and the spirit was shot out 

 of the boily by the same charge of powder 

 that announced the birthday of liberty — the 

 liberty to torture and to slay. 



As gmipowder is one of the principal actors 

 on the stage now, we will venture to say a 

 few words on its chemical nature, and why it 

 is explosive. Gimpowder is explosive be- 

 cause it burns so rapidly, and it burns rapidly 

 because it contains within itself both that 

 which burns and that which supports com- 

 bustion. If we 

 would' burn 

 charcoal or sul- 

 phur, we must 

 supply them 

 w i t h ox\gen 

 from without, 

 but, when they 

 are mixed with 

 nitre, or salt- 

 petre, the lat- 

 ter furnishes the 

 oxygen, and 

 every particle 

 of sulphur finds 

 itself in imme- 

 diate contact 

 with oxygen 

 enough to con- 

 sume it. Yet 

 the velocity 

 with which 

 flame travels in 

 gunpowder, is 

 as a snail's pace 

 compared with 

 that in some 

 other explo- 

 sives. In a mixture of oxygen and hydro- 

 gen, flame travels more than 33 yards 

 per second. When substances rich in 

 oxygen — which is easily liberated by heat — 

 are mixed with combustible substances, the 

 mixture is liable to explode. Flowers of sul- 

 phur, mixed with potassium chlorate, deto- 

 nate when triturated, and a lecturer recently 

 attempted to exhibit this experiment, when 

 the mass took fire, and a flame shot up higher 

 than his head, depriving him of a consider- 

 able portion of his elegant whiskers, and 

 inflicting a bad burn. Chlorate of potash 

 finds use, for the same reason, in the parlor 

 match. Oxygen is usually prepared by heat- 

 ing chlorate of potash, which is generally 

 mixed with manganese dioxide. One un- 

 lucky chemist mistook sulphide of antimony 

 for the oxide of manganese. As soon as heat 

 was applied, the sulphur united with the nas- 



cent oxygen, and now that experimenter 

 sports one glass eye, and is thankful to have 

 one of the natural members and part of his 

 nose left him. This mixture is employed in- 

 stead of a fulminate in the needle-gun. 



Many combustible substances, when finely 

 divided and mixed with air, explode. Hence 

 we often read of explosions in flour mills, 

 and some time ago a large bin of saw-dust 

 exploded in Greenpoint, N. Y. 



Sometimes the explosion is due to the de- 

 composition of a solid body, which then 

 forms a very large volume of gas at a \er\- 

 high temperatine. Such is the case with 

 nitro-glycerine and other nitro-compounds. 

 The decomposition takes place in them with 

 such rapidity that, while they make excellent 



most common use. Designolle's powder con- 

 tains nine parts of picrate to one of nitrate 

 of potash, mixed witli charcoal. Brugere's 

 powder contains fifty-four parts of picrate of 

 ammonia and forty-six of saltpetre. 



SMUBiamjitL 



Fig. I. 



explosives for destructive purposes, they can- 

 not be used for propelling projectiles. Nitro- 

 cellulose is one of the least dangerous of the 

 nitro-compoimds. According to the experi- 

 ments of Eder, there are five kinds of nitro- 

 cellulose containing from two to five mole- 

 cules of NO3. When any of these so-called 

 pyroxylines are satiuated with nitro-glycerine, 

 a very powerful explosive is obtained, which 

 has a ■ gummy appearance, and is called 

 explosive-gelatine. The addition of camphor 

 is said to render it quite safe from accidental 

 explosion. 



Picric acid, which is rcall}' trinitro-phenol, 

 formed by the action of nitric acid on carbolic 

 acid, has been used chiefly in France for mak- 

 ing an explosive substance for filling torpedoes 

 and bombs. A gunpowder in which picrate 

 of potash takes the place of the saltpetre, is its 



A HIBERNATING FISH. 

 Professor Edouard Heckel, of the Paris 

 Museum of Natural History, gives an inter- 

 esting account in Le Natiiraliste of a semi- 

 amphibious fish, — the Protopterns annectens, 

 Owen, — which is found in the warm waters 

 of certain African rivers. As will be seen 

 from the engraving (copied from the above 

 journal), it is a long, slender fish, resembling 

 an eel, and, in the rainy season, when the 

 rivers are high and the adjacent rice-fields 



flooded, it seeks 

 the overflowed 

 land. As the 

 rivers fall, it 

 burrows into 

 the mud, doub- 

 ing itself up 

 into an oval 

 ring, and foim- 

 ing a sort (jf 

 nest, in which 

 it remains in 

 safety during 

 the s e V e n 

 months of dry 

 weather. (Fig. 

 2.) A small 

 opening is left 

 for air, and, in 

 a short time, a 

 sort of glue ex- 

 udes from the 

 b o d V of the 

 animal, whicli 

 mixes with the 

 earth of the 

 sitlcs of the liiu'- 

 row, and hard- 

 ens to a solid shell, perfectly protecting the 

 occupant from injury. Encased in these nat- 

 ural cells, the specimens described by Pro- 

 fessor Heckel were brought to Paris, and, 

 when opened and placed in water, the curi- 

 ous animals soon revived, and lived for 

 several days, until they succumbed to the 

 attack of a parasitic alga;. 



The Protopterus seems to be an intermedi- 

 ate form between a fish and a batrachian. 

 Frogs, as is well known, hibernate in the 

 mud, but this animal, in its general appear- 

 ance, much more closely resembles a fish. 

 No details are given concerning the structure 

 of its respiratory apparatus, but it must be 

 considerably modified from that of tiic true 

 fishes to support life during its long- 

 sojourn in the dried mu<l of the African 

 river banks, under the rays of a trojjical sini. 

 When the cells in which the}' were encased 



