CHEMISTRY. 



93 



distinctly crystalline state, by various manipu- 

 lations and the application of suitable very high 

 degrees of temperature. 



Protection of Woodwork from Fire. At one 

 ,of the collieries at Ibbenbiieren, Westphalia, 

 the woodwork is protected from fire by being 

 painted with a mixture consisting of 5 parts 

 of alum, 7 parts of rye-meal paste, and 30 

 parts of previously-washed, i. e., finely divided 

 clay (this mixture is used for woodwork not 

 exposed to open air) ; for woodwork so ex- 

 posed, a mixture is used consisting of 2 parts 

 of crystallized sal-ammoniac, 1 part of white 

 vitriol (commercial sulphate of zinc), 2 parts 

 of joiners' glue, 20 parts of zinc-white, and 30 

 parts of water. These mixtures have been 

 found to prevent wood bursting into flame on 

 ignition, and greatly to delay its destruction 

 even when severe fires are raging. 



Decomposition ly Sunlight. M. Morren 

 communicates to the Comptes Rendus for Au- 

 gust 9th some observations on the phenomena 

 of decomposition produced by sunlight. While 

 repeating some of Prof. Tyndall's experiments, 

 but applying, instead of electric light, the bright 

 sunlight of Marseilles's clear sky, he discov- 

 ered that several inorganic substances are de- 

 composed when a ray of sunlight is made to 

 pass through them; among these sulphurous 

 acid gas is enumerated, this gas being decom- 

 posed into oxygen and vapor of sulphur. This 

 phenomenon is caused, according to the au- 

 thor, by a peculiar dissociation called into 

 play by the vibratory motion of the light, 

 which has the effect of breaking up the chemi- 

 cal combination ; by means of spectrum analy- 

 sis the author has discovered that the activity 

 of the light in this aspect depends partly upon 

 its color, and partly upon the refrangence and 

 the nature of the decomposed substance. The 

 author has also found that a thin layer of sul- 

 phate of quinine of no more than 4 or 5 mm. 

 thickness entirely arrests the chemical rays, as 

 if it were a thick, yellow-colored piece of glass. 

 The author states that the chemical effects of 

 highly-heated platinum for instance, the de- 

 composition of water by that metal are due 

 to the accumulation of more and more refran- 

 gent rays. 



Hydrofluoric Acid. Mr. G. Gore read a 

 paper before the Eoyal Society in January, 

 giving a full description of the leading physi- 

 cal and chemical properties of anhydrous 

 hydrofluoric acid, and of the various prop- 

 erties of pure aqueous hydrofluoric acid. 

 He obtained his anhydrous acid by heating dry 

 double fluoride of hydrogen and potassium to 

 redness in a suitable platinum apparatus. 

 Nearly all the manipulations with the acid 

 were effected while the vessels containing it 

 were immersed in a strong freezing mixture of 

 ice and crystallized chloride of calcium. The 

 author describes the pure anhydrous acid as a 

 highly-dangerous substance; a perfectly col- 

 orless and transparent liquid at 60 F., very 

 thin and mobile, extremely volatile, and densely 



fuming in the air at ordinary temperatures, and 

 absorbs water very greedily from the atmos- 

 phere. It was perfectly retained in a platinum 

 bottle, the bottle having a flanged mouth with a 

 platinum plate secured with clamp-screws, and 

 a washer of paraffin : 



A number of attempts were made, finally with suc- 

 cess, to determine the molecular volume of the pure 

 anhydrous acid in the gaseous state, the acid in these 

 cases being prepared by heating pure anhydrous fluo- 

 ride of silver with hydrogen in a suitable platinum 

 apparatus over mercury. Particulars are given of 

 the apparatus employed and of the manipulation. 

 The results obtained show that one volume of hydro- 

 gen, in uniting with fluorine, produces not simply 

 one volume of gaseous product as it does when unit- 

 ing with oxygen, but two volumes, as in the case of 

 its union with chlorine. The gaseous acid transferred 

 to glass vessels over mercury did not corrode the 

 glass, or render it dim in the slightest degree during 

 several weeks, provided moisture was entirely absent. 



The specific gravity of the anhydrous liquid acid 

 was several times determined, both in a specific- 

 gravity bottle of platinum, and also by means of a 

 Slatinum float submerged and weighed in the acid, 

 oncordant and reliable results were obtained ; the 

 specific gravity found was 0.9879 at 55 Fahr., that 

 of distilled water being 1.000 at the same temper- 

 ature. 



Numerous experiments were made of electrolyzing 

 the anhydrous acid with anodes of gas-carbon, car- 

 bon of lignum-vitae, and of many other kinds of 

 wood, of palladium, platinum, and gold. The gas- 

 carbon disintegrated rapidly ; all the kinds of char- 

 coal flew to pieces quickly, and the anodes of palla- 

 dium, platinum, and gold, were corroded without 

 evolution of gas. The acid with a platinum anode 

 conducted electricity much more readily than pure 

 water ; but with one of gold it scarcely conducted at 

 all. 



To obtain an idea of the general chemical behavior 

 of the pure anhydrous acid, numerous substances 

 (generally anhydrous) were immersed in separate 

 portions of the acid in platinum cups, kept at a low 

 temperature (0 to 20 Fahr.). The acid had scarcely 

 any effect upon any of the metalloids or noble metals, 

 and even the base metals in a state of fine powder did 

 not cause any evolution of hydrogen. Sodium and 

 potassium behaved much the same as with water. 

 Nearly all the salts of the alkali and alkaline earth- 

 metals produced strong chemical action. The anhy- 

 drous acid decomposed all carbonates with efferves- 

 cence, and those of the alkaline earth and alkali- 

 metals with violent action. Borates of the alkalies 

 also produced very strong action. Silico-fluorides of 

 the alkali-metals dissolved with effervescence. All 

 sulphides, except those of the alkaline earth and 

 alkali-metals, exnibited no change ; the latter evolved 

 sulphuretted hydrogen violently. Bisulphite of so- 

 dium dissolved with effervescence. Sulphates were 

 variously affected. The acid chromates of the alkali- 

 metals dissolved with violent action to blood-red 

 liquids, with evolution of vapor of fluoride of chro- 

 mium. Cyanide of potassium was violently decom- 

 posed, and hydrocyanic acid set free. Numerous 

 organic bodies (specified) were also immersed in the 



pentine it exploded, and produced a blood-red liquid. 

 Gutta-percha, india-rubber, and nearly all the gums 

 and resins, were rapidly disintegrated, and generally 

 dissolved to red liquids. Spermaceti, stearic acid, 

 and myrtle wax, were but little affected, and paraffin 

 not at all. Sponge was but little changed. Gun- 

 cotton, silk, paper, cotton wool, calico, gelatine, and 

 parchment, were instantly converted into glutinous 

 substances, and generally dissolved. The solution of 



