348 SOLID PARTS OF ANIMALS. 



The insoluble residue after this treatment with water and al- 

 cohol burned without swelling up, and gave out white fumes, 

 having the smell of burning wood. It was neither discoloured 

 by chlorine nor by sulphurous acid. It dissolved with efferves- 

 cence in muriatic acid, which took up two-thirds of it, and left 

 a black paste. From this solution ammonia threw down a small 

 quantity of brown matter, which, when calcined, did not lose its 

 colour. It was chiefly oxide of iron. The liquid to which the 

 ammonia had been added gave a gray precipitate with potash, 

 which was chiefly carbonate of lime. 



When caustic potash is poured upon the residue of spider's webs 

 previously treated with water and alcohol, it dissolves it partially, 

 while a little ammonia is given out. From this solution an acid 

 throws down a black tasteless powder, which slightly swells when 

 heated, and when dried is brittle, and has the aspect of a resin. 

 It amounts to about one-twelfth of the exhausted spider's webs 

 made use of. It is partly soluble in volatile oils. 



The aqueous extract of spider's webs when digested in alcohol 

 gave out about one-seventh of its weight. The alcohol, when 

 evaporated, left a brown matter, pretty deliquescent, and having 

 a sharp taste. It swelled considerably on burning coals, and 

 burnt rapidly as if it had contained nitre. It contained chloride 

 of calcium, and a sulphate probably of ammonia. 



What remained of the aqueous extract after treatment with 

 alcohol was lighter coloured than before, was in powder, and had 

 a slightly pungent taste. On hot coals it did not swell, but left 

 an abundant residue. Sulphuric acid poured on it occasioned 

 no smell, nor did quicklime evolve ammonia. 



When spider's webs were distilled per se they gave out water 

 slightly coloured at first, but becoming darker as the process 

 went on. Then a black thick oil came over with inflammable 

 gas and carbonic acid. The smell of ammonia was perceptible, 

 and the charcoal remaining amounted to about half the weight 

 of the spider's webs employed. This coal, when incinerated, left 

 two-thirds of its weight, half of which was soluble in muriatic acid, 

 and the residue was silica and charcoal, the muriatic acid solu- 

 tion being evaporated left sulphate of lime. When spider's webs 

 were incinerated in an open vessel, the ashes consisted of sul- 

 phate of lime, common salt, and carbonate of soda, a little oxide 

 of iron, silica, and alumina. 



