132 



HAKDWICKE'S SCIENCE-GOSSIP. 



presence of a wick, and is tlierefore perfectly safe ; 

 when burning, it splits up into olefiaut gas, thus 

 producing a brilliant white light. To sum up : from 

 the two waste products of coal in the manufacture 

 of gas are obtained carbonate, chloride, and sul- 

 phate of ammonium, sulphur and sulphuric acid^ 

 coal-naphtha, benzol, nitro-beuzol, aniline, carbolic 

 and carbazotic acids, and solid paraffin. 



The next division of this interesting subject is 

 rags. First and foremost of the many applications 

 of this humble material is the manufacture of paper ; 

 for this purpose M'c buy from other nations no less 

 than 15,000 tons of rags annual!)', besides using 

 70,000 tons from the waste of our own population; 

 the whole representing a money value of £700,000. 

 The trausTormation effected by the action of certain 

 chemicals on paper is very striking. A sheet of 

 common white blotting-paper, which will scarcely 

 bear its own weight when wetted, is converted in 

 a few seconds by the action of sulphuric acid into 

 a substance 'possessing all the properties of ordi- 

 nary animal parchment, and so strong that it can be 

 only broken with difficulty. Great as this change 

 is, strange to say, no chemical alteration has really 

 taken place ; the acid merely produces a molecular 

 change, and is entirely washed away at tlie end of 

 the process. Hags from woollen materials undergo 

 many peculiar metamorphoses ; old clo' crier s first 

 collect them ; they are then successively converted 

 into mungo, shoddy, and devil's dust, and reap- 

 pear as ladies' superfine cloth ; they then degenerate 

 into druggets, and are finally used for the manufac- 

 ture of flock-paper. After undergoing all these trans- 

 formations they are used by the agriculturist as 

 manure, on account of the large amount of nitrogen 

 they contain. The presence of this element makes 

 them of great use also to the chemical manufacturer ; 

 he boils them down with pearUoli, horns and hoofs 

 of cattle, old iron hoops, blood, clippings of 

 leather, and broken horseshoes, and produces the 

 beautiful yellow and red salts known as the prus- 

 siatcs of potash. Prom these again the rich and 

 valuable pigment called Prussian blue is made ; and 

 thus do our old rags enter upon a fresh career of 

 beauty and usefulness, to form in their turn other 

 waste products, which may again be utilized through 

 the power of man's intelligence. 



The vast and important subject of bones now 

 demands attention. Of these we import more than 

 £400,000 worth, and the uses to which they are 

 applied arc endless. Bones are composed of half 

 their weight of phosphate of lime, about a third of 

 their weight of cartilage or gelatine, and the re- 

 mainder of earthy matters. The gelatine is ex- 

 tracted by boiling water under pressure, and is 

 used to stiffen calico, &c. ; when purified, it con- 

 stitutes the nutritious aliment known as calf's-foot 

 jelly. 



When bones are heated without access of air, the 



organic matter of the cartilage is decomposed, oily 

 products passing over, and a black carbonaceous 

 residue being left : tbis is bone-black, or animal 

 charcoal, greatly used as a deodorizer and disin- 

 fectant. Bones, when calcined and heated witli 

 sulphuric acid, yield superphosphate of lime, so 

 highly esteemed as a manure. The last and cer- 

 tainly the most important application of bones is 

 the manufacture of phosphorus. The bones are 

 first burnt to remove all traces of animal matter ; 

 the resulting bone-earth, as it is called, is then 

 subjected to the action of sulphuric acid, by which 

 superphosphate of lime is produced. This acid 

 phosphate is then mixed with charcoal and strongly 

 heated in a retort, when it splits up into normal 

 phosphate and phosphoric acid, the latter being 

 finally reduced by the charcoal to phosphorus, 

 while hydrogen and carbonic oxide are liberated as 

 gases. The combustible and poisonous properties 

 of phosphorus make it very dangerous to employ 

 in the arts ; but Professor Schrotter discovered 

 that when ordinary phosphorus Mas heated for 

 some time in a closed vessel to a temperature of 

 470° it lost its power of igniting spontaneously 

 and became of a deep red colour. By making use 

 of this discovery, matches can now be made with- 

 out danger either to those who manufacture them 

 or to those who use them. The safety-match is 

 made by putting the oxidizing material alone on 

 the match, the red phosphorus being mixed with 

 emery and pasted on the side of the box. 



We have thus mentioned a few of the valuable 

 applications of substances which some years ago 

 were looked upon as utterly worthless. Coal-tar, 

 rags, and bones rise from the sewer and dust-heap, 

 and are transformed by chemistry into gorgeous 

 luxuries and necessities of civilization, giving em- 

 ployment in their transformations to thousands of 

 our vroiking classes. C. Leicester. 



ON THE ECONOMY OF THE ERESH- 

 WATER POLYP. 



HAVING for more than two years past had a 

 number of Hydras in small glass aquaria 

 under my (I* might almost say daily) observation, 

 1 thought, simple and limited as those observations 

 may be, that they perhaps would prove interesting 

 to the readers of Science-Gossip. The Hydras are 

 most interesting animals, and have long attracted 

 the attention of naturalists generally, on account of 

 their extraordinary powers of reproduction. The 

 Hydra vulgaris, which is the same as I have in my 

 glasses, was discovered by Leeuwenhok, in 1703 ; 

 but its wonderful power of digestion, and of nndti- 

 plication after division, were first discovered by 

 Tiembley in 1740. 



Having noticed, at the end of last December, that 



