Caustic Lime Research Articles

On “Getting” Coal by Means of Caustic Lime

IN stating that the caustic lime process was likely to have only a limited application in coal-mining operations, it was not my intention to convey the impression, as Mr. Mosley appears to think it was, that the area of its usefulness would necessarily be a small one. On the contrary, I believe it could be successfully employed in getting coal under a large variety of circumstance.

IV. On the solubility of solids in gases. II

In a former paper it was pointed out that a solid dissolved in a liquid was not deposited from solution when the liquid passed through the critical point into the gaseous state, and the conclusion drawn that solids are soluble in gases. I have shown in another paper that it is probable that after a liquid passes its critical point it becomes a vapour or gas, and this quite independent of pressure, and that the cohesion limit for any one substance lies more in the direction of an isothermal line than a continuation of the boiling line. Before, however, I had carried out that work, I determined to make sure that a truly gaseous state had been reached, and the fluid containing the solid was raised to 150° above its critical point, and the gaseous solution expanded to nearly twice its liquid volume, and still the solid remained in solution. In these circumstances it was found that non-volatile solids were retained in solution in truly gaseous menstrua. In the second paper referred to, I have pointed out some of the difficulties which beset such an investigation ; and when it is remembered that only air-baths can be used, the temperature being over 200° and sometimes over 300°, and that very many liquids dissociate under these temperatures, it will be seen that conclusions should be drawn only from substances perfectly free from suspicion. All the experiments, therefore, which I have performed in iron tubes cannot bear on a discussion in this matter ; and I shall defer going into the natural minerals formed artificially from aqueous solution at a red-heat till another paper. For high temperatures glass does not do, as every variety of it is easily decomposed by water ; but by the use of rock crystal blocks I have obtained some results of interest where the action of the water can be seen. However, I intend in this paper to treat in a fuller manner of work touched upon in former papers. One of the first pieces of work I set about to finish was to determine whether or not the critical points were altered by the introduction of a solid into solution. In a former paper it was thought that the critical point of alcohol containing potassic iodide in solution was higher than pure alcohol, but subsequent experiments determined me to go into the matter again. The cause was this. I found that absolute alcohol if exposed to air for a very short time takes up sufficient moisture to alter its critical point ; and I considered that in preparing the solution of the iodide some moisture might have been introduced. The experiments were repeated in the following manner. Some common absolute alcohol was placed in a flask with caustic lime, freshly burned, and cohobated for a week. The flask was then fitted with the arrangement shown in the diagram. The tube connected with the drying arrangement is turned up at the lower end, so that the exit tube may be slipped into it. A current of air desiccated over sulphuric acid is passed through this for some time, and the tube A then slipped out of the recurved end in the flask, turned round so as to clear it, and pushed down till it is below the level of the desiccated alcohol, which is forced up into the experimental tube sealed or connected to A. In this way, any quantity of alcohol, which has never been removed from contact with lime, can be introduced into the working tube. A portion of fused potassic iodide placed in the experimental tube before the experiment enables a saturated solution to be prepared out of contact with air when the liquid is sealed up. Twenty experiments were done with pure alcohol, and twenty with alcohol saturated with potassic iodide. The pure alcohol had the specific gravity .7928 at 15°.5.

III. On the state of fluids at their critical temperatures

III. On the state of fluids at their critical temperatures

XV. On the specific heat and other physical characters of mixtures of methylic alcohol and water, and on certain relations existing between the specific heat of a mixture or solution and the heat evolved or absorbed in their formation

The pure methylic alcohol was prepared according to the following process, devised by Mr. Chapman. Rectified wood-spirit is mixed with its own bulk of a saturated solution of calcium chloride, the mixture is heated to boiling and allowed to stand over night. The layer of oil found floating on the surface is carefully removed, and the fluid underneath is mixed with about one volume per cent. of a saturated solution of lead acetate. An amount of sulphide of ammonium, not quite sufficient to precipitate all the lead, is next added, the precipitate, which carries down much colouring-matter and many minute globules of oil, is filtered off, or allowed to subside, and the clear fluid is distilled. To this distillate caustic soda in coarse powder is added, and after standing some time it is diluted with water and again distilled; much resinous matter is thus removed, and the acetate of methyl is decomposed. The specific gravity of this second distillate is now brought to about 82 (if necessary, by treatment with potassium carbonate), after which it is mixed with one fourth of its bulk of a saturated solution of bisulphite of ammonium. The mixture is allowed to stand for several days, and is then filtered and distilled from a water-bath; to the distillate a little sulphuric acid is added, and it is then redistilled, also from a water-bath. Finally a slight excess of caustic soda is added, and the liquid is once more distilled, when pure methylic alcohol passes over, which is rendered anhydrous by several distillations over caustic lime. The purity of the spirit is tested by oxidizing 20 grammes of it with an excess of bichrom ate of potassium and sulphuric acid, when it should yield nothing but carbonic acid and water. The spirit thus prepared was perfectly miscible with water in every proportion; it had at 10°C. a specific gravity of ⋅81371, boiled at 58°⋅6 C. at a pressure of 757⋅4 millims., and had a specific heat of 58⋅325 between the temperatures of 60° and 18°.

II. On Fluoride of silver.—Part I

This communication treats of the formation, preparation, analysis, composition, common physical properties, and chemical behaviour of fluoride of silver. The salt was prepared by treating pure silver carbonate with an excess of pure aqueous hydrofluoric acid in a platinum dish, and evaporating to dryness, with certain precautions. The salt thus obtained invariably contains a small amount of free metallic silver, and generally also traces of water and of hydrofluoric acid, unless special precautions mentioned are observed. It was analyzed by various methods: the best method of determining the amount of fluorine in it consisted in evapoiating to dryness a mixture of a known weight of the salt dissolved in water, with a slight excess of pure and perfectly caustic lime in a platinum bottle, and gently igniting the residue at an incipient red heat until it ceased to lose weight. By taking proper care, the results obtained are accurate. The reaction in this method of analysis takes place according to the following equation, 2AgF + CaO = CaF 2 +2Ag + O. Sixteen parts of oxygen expelled equal thirty-eight parts of fluorine present. One of the methods employed for determining the amount of silver consisted in passing dry ammonia over the salt in a platinum boat and tube at a low red heat, The results obtained in the various analyses establish the fact that pure fluoride of silver consists of 19 parts of fluorine and 108 of silver.

Societies and Academies

LONDONRoyal Society, January 13.—The following papers were read:-“On the Mineral Constituents of Meteorites,” by Nevil Story-Maskelyne, M.A., Professor of Mineralogy in the University of Oxford, and Keeper of the Mineral Department, British Museum. Communicated by Prof. H. J. Stephen Smith, F.R.S. [We are compelled to postpone an abstract of this paper.] “On Fluoride of Silver.” Part I. By George Gore, F.R.S. This communication treats of the formation, preparation, analysis, composition, common physical properties, and chemical behaviour of fluoride of silver. The salt was prepared by treating pure silver carbonate with an excess of pure aqueous hydrofluoric acid in a platinum dish, and evaporating to dryness, with certain precautions. The salt thus obtained invariably contains a small amount of free metallic silver, and generally also traces of water and of hydrofluoric acid, unless special precautions mentioned are observed. It was analysed by various methods: the best method of determining the amount of fluorine in it consisted in evaporating to dryness a mixture of a known weight of the salt dissolved in water, with a slight excess of pure and perfectly caustic lime in,a platinum bottle, and gently igniting the residue at an incipient. red heat until it ceased to lose weight By taking proper care, the results obtained are accurate. The reaction in this method of analysis takes place according to the following equation: 2AgF +CaO= CaF.2 + 2Ag + 0. Sixteen parts of oxygen expelled equal thirty-eight parts of fluorine present. One of the methods employed for determining the amount of silver consisted in passing dry ammonia over the salt in a platinum boat and tube at a low red heat. The results obtained in the various analyses establish the fact that pure fluoride of silver consists of nineteen parts of fluorine and 108 of silver. Argentic fluoride is usually in the form of yellowish brown ear thy fragments; but when rendered perfectly anhydrous by fusion, it is a black horny mass,. with a superficial satin lustre, due to particles of free silver. It is extremely deliquescent and soluble in water; one part of the salt dissolves in '55 part by weight of water at 15° “5 C.; it evolves heat in dissolving, and forms a strongly alkaline solution. It is nearly insoluble in absolute alcohol. The specific gravity of the earthy-brown salt is 5 “852 at 15°'5 C.; the specific gravity of its aqueous solution, at I5°*5 C, saturated at that temperature, is 2 61. By chilling the saturated solution, it exhibited the phenomenon of supersatuiation and suddenly solidified, with evolution of heat, on immersing a platinum plate in it The solution is capable of being crystallised, and yields crystals of a hydrated salt; the act of crystallisation is attended by the singular phenomenon of the remainder of the salt separating in the anhydrous and apparently non-crystalline state, the hydrated salt taking to itself the whole of the water. The fused saltj after slow and undisturbed cooling, exhibits crystalline markings upon its surface. The dry salt is not decomposed by sunlight; it melts below a visible red heat; and forms a highly lustrous, mobile, and jet-black liquid. It is not decomposed by a red heat alone.; but in the state of semi-fusion or of complete fusion it is rapidly decomposed by the moisture of the air with separation of metallic silver; dry air does not decompose it. In the fused state it slightly corrodes vessels of platinum, and much more freely those of silver. The salt in a state of fusion with platinum electrodes conducts electricity very freely, apparently with the facility of a metal, and without visible evolution of gas or corrosion of the anode; a silver anode was rapidly dissolved by it, and one of lignum-vitas charcoal wras gradually corroded.

On caustic lime in blast furnaces

On caustic lime in blast furnaces

On the use of caustic lime, instead of limestone, in blast furnaces

On the use of caustic lime, instead of limestone, in blast furnaces

On the use of caustic lime, instead of limestone, in blast furnaces

On the use of caustic lime, instead of limestone, in blast furnaces

On the use of caustic lime, instead of limestone, in blast furnaces

On the use of caustic lime, instead of limestone, in blast furnaces

On the use of caustic lime, instead of limestone, in blast furnaces

On the use of caustic lime, instead of limestone, in blast furnaces

On the use of caustic lime, instead of limestone, in blast furnaces

On the use of caustic lime, instead of limestone, in blast furnaces

On the Formation and Destruction of Limestone, and some of the Minerals which accompany it

In referring to the earliest periods of this earth’s history, we have positive evidence of its having once existed in a purely incandescent state; it consequently requires the assistance of very little chemical knowledge to convince us that such compounds as we now find upon its surface, could not then exist. We have ample proofs, from the every-day operation in our own furnaces, that the application of a violent heat to mixed mineral compounds alters their affinities to such an extent as to give rise to products of an entirely different character; such minerals as chalk, marble, or limestone rock, which consist of carbonic acid and lime, would lose that volatile acid at a high temperature, and caustic lime would be the result, as we find to be the case in the common process of burning. If, instead of heating the carbonate alone, we previously mix it with some of our sandstone, which consists principally of silica, we should not only expel the carbonic acid, as above stated, but a new compound, called silicate of lime, would be formed in its place. This decomposition is not confined to the carbonate of lime; any other salt containing a volatile acid would be acted upon by silica at a high temperature in a similar manner; hence we may fairly conclude that, during the igneous period just named, all the lime which now lies embedded in the form of limestone rocks, was then in the state of a silicate. Where, then, was the ...