206 ANNUAL OF SCIENTIFIC DISCOVERT. 



mio;ht have been thrust into the lamp with safety; the vapor 

 would have ignited, but no explosion would have taken place." 



HYDRIODIC ACID. 



Prof. Winkler uses the following improved process, in order to 

 avoid loss of iodine, which is not uncommon in the officinal 

 method, beside yielding an acid of much greater strength if 

 desired. Bisulphide of carbon is saturated with iodine in a tall 

 cylinder or flask, and a sufficient quantity of water is poured on, 

 according to the proposed strength of the acid. The tube from 

 the sulphuretted hydrogen apparatus reaches to the bottom of the 

 cylinder, and the gas is decomposed in the same manner, while 

 the sulphur as it separates dissolves in the bisulphide. As soon as 

 the hitter is decolorized the current of gas is stopped, and the 

 watery solution is separated from the oily solution of sulphur by 

 means of a moistened filter. After heating it for a sliort time at 

 the boiling-point in a retort, the acid will be clicmically pure, 

 while the bisulphide is also recovered by simple distillation. For 

 the preparation of hydrobromic acid this process is not applicable, 

 because it is not possible to prevent altogether the formation of 

 sulphide of bromine. 



BLEACHING OF TISSUES. 



Some recent researches by M. Kolb on the bleaching of tissues 

 will be found of interest to those engaged in this department of 

 the arts. We give a condensed account of these experiments as 

 contained in the London " Chemical News "" : — 



Flax was the fibre chiefly experimented with, alkalies being 

 the reagents whose eff'ects were studied, the object being to fix 

 precisely the nature of the substance which passes by the name 

 of resin, gummy matter, gum-resin, sajDonifiable matter, etc. 

 Elementary analysis gave no information ; it gave figures which 

 closely approached the percentage composition of cellulose. The 

 employment of various solvents used in organic chemistry, on the 

 contrary, led to certain conclusions by a chain of facts. The fibre, 

 after treatment witli alkalies, furnished strongly colored lyes, 

 which had a certain tendency to mould ; this result suggested the 

 idea of a saponification, and led to the examination, as solvents, 

 of alcohol, ether, and essential oils. The yellow coloring matter 

 is completely insoluble, and these liquids only remove from the 

 fibre a white fatty matter and a green essence, the penetrating 

 odor of which is found slightly perceptible in bleachers' lyes. 

 Thewhole only constitutes 48 per cent, of the weight of the fibre, 

 and is the portion really saponifiable in caustic alkalies; the alka- 

 line carbonates leave this fatty matter in the fibre, which becomes, 

 at the same time, more supple. After exhaustion by alcohol, the 

 fibre, boiled in weak potash, soda, or ammonia solution, gave, in 

 three cases, a loss in weight of 22 per cent. Carbonate of soda 



