My purpose this evening is to describe a process for the estimation of potassium as acid tartrate,- -a process which has the advantage of being direct, and which gives results much more rapidly than can be obtained by any other means, while for accuracy they compare favourably even with those obtained by platinic chloride.

The occasion which led me to estimate potassium as acid tartrate was a series of experiments on the process of Messrs. Duncan and Newlands for separating potassium from the low products of sugar-houses by the addition of sulphate of alumina, and the consequent production of potassium alum. To avoid an excess of sulphate of alumina, which would be a waste, it became necessary to ascertain the quantity of potassium in each batch of products. For this determination platinic chloride is not very well adapted, as the first requisite was celerity rather than accuracy. The use of platinic chloride requires, in the first place, a thorough destruction of the organic matter by heat. The ashes, obtained as sulphates, are treated, in the next place, by an excess of barytic chloride, which gives a solution containing the chlorides corresponding to the sulphates in the ashes, and an excess of barytic chloride. From this solution, properly reduced in volume, potassium may be precipitated by platinic chloride.

Instead of this series of preparatory operations, to be followed by those required by the nature of the double chloride, it occurred to me, at first, to treat a small quantity of the low saccharine product by an excess of sulphate of alumina, and, from the quantity of alum obtained, to calculate that of sulphate of alumina required for the quantity of low products to be treated on a large scale. This idea afterwards led to that of substituting tartaric acid for sulphate of alumina, and, on trying tartaric acid, the results were so uniform and satisfactory that I was induced to apply it to the determination of potassium in compounds of all kinds.

Cream of tartar presents, over every other compound of potassium, the incomparable advantage that, while its solubility is very feeble, the estimation of it, by a titrated alkaline solution, is an operation that only takes a few minutes. To determine the quantity of cream of tartar that we may have to analyse it can be placed in a beaker glass with a sufficiency of water, which it is advantageous to heat, to increase the solubility of the acid tartrate. A few drops of litmus solution will impart a red colour, which will persist as long as any cream of tartar remains in the solution. If now we add a solution of potassa, drop by drop, to the contents of the beaker glass, the acid tartrate will be converted to the basic, and, while the change is going on, the unconverted cream of tartar will continue to colour the litmus red. When the last particle of acid tartrate has been converted to the basic, an addition of the smallest particle of potassa solution will turn the litmus blue. We may now note that the quantity of potassa added to convert the acid tartrate into the basic is exactly the same as the quantity already in combination as acid tartrate. We may note, moreover, that the equivalent of cream of tartar is exactly four times greater than the equivalent of potassa, so that if we have added I grm. of potassa to turn the litmus blue, we must have had 4 grms. of acid tartrate, holding in combination I grm. of potassa. After every addition of potassa the contents of the beaker should be thoroughly stirred, to dissolve the portions of acid tartrate which are undissolved, but which gradually become soluble as potassa is added. Before the change to the basic condition is complete the crystals of bitartrate disappear, and the red solution becomes perfectly clear. This is an indication that the end is near.

That acid tartrate of potassium is so well adapted to

CHEMICAL NEWS Dec. 1, 1876.

being tested by a titrated alkaline solution is the quality which, combined with its feeble solubility, recommended it as the compound in which to obtain potassium for analysis. We must, however, increase its insolubility if accurate results are to be obtained, and this can be easily accomplished by means of alcohol.

The insolubility of cream of tartar in a mixture of alcohol and water is greater than in pure water. The following table given by Chancel shows the solubility of cream of tartar in water at several temperatures :—

Having had occasion to use this table repeatedly, I have verified these numbers and found them correct. Chancel has also given us another column, representing the number of grammes of cream of tartar which 100 c.c. of water, containing 10 per cent alcohol, will dissolve at the same temperature. These numbers are nearly 57 per cent of those corresponding to pure water.

To discover the minimum of alcohol which will render a mixture with water incapable of dissolving cream of tartar, a great many experiments were made, and it was found that the mixture containing 60 per cent of alcohol fulfils this condition. By bringing all the liquids containing acid tartrate of potassium to the condition of containing at least 60 per cent of alcohol in volume, I have been able to obtain the whole potassium in the shape of insoluble cream of tartar.

Alcohol of this strength is not, however, to be used from the first, as it may in some cases interfere with the solution of the compounds to be analysed, and sometimes our potassium may be precipitated in other forms than cream of tartar. It should only be used at the last stage, immediately before throwing the precipitate on a filter, so that the acid tartrate in solution may be thrown down. It should also be used to wash the precipitate on the filter, to free it from tartaric and acetic acid, as we shall see hereafter.

To enable me to explain the method of procedure in estimating potassium as acid tartrate, let me take the simplest case which can present itself, which is the analysis of a solution of pure potassa in water. Suppose we have a deci-normal solution of potassa, containing 47 m.grms. of potassa for every c.c. of solution. If we drop to c.c. in a beaker glass we may convert the whole of it into acid tartrate if we add a sufficient quantity of tartaric acid. As to what constitutes a sufficiency, we may note that there ought to be enough to precipitate all the potassium to be tested, the minimum being four times as much acid as there is potassium in the compound. We may, however, use a quantity of tartaric acid six times greater than the quantity of potassium to be precipitated. Beyond this, in the presence of alcohol, the precipitate is apt to contain an excess of acid. I am unable to say in what shape this excess of acid exists; but if we use a marked excess of tartaric acid, as much as ten or twelve times more than the potassium to be precipitated, the test by a titrated solution of potassium will give an excess of 2 or 3 per cent. If we have any means of getting approximately at the quantity of potassium in a substance to be tested, we should use six times as much tartaric acid as the supposed quantity of potassium. If, on making the test, we should find that we have gone too wide of the mark, the quantity obtained in a first test will allow us to determine, to a certainty, the quantity to be used in a

Chlorine, Bromine, Iodine, and Fluorine.
By Dr. E. MYLIUS, of Ludwigshafen.

As an interesting fact we may call to mind that at the Paris Exhibition in 1867 large quantities of the silicofluorides of sodium and barium, of soda-ash, and caustic soda were displayed by Tessié du Motay as products obtained by the application of fluoride of silicon and hydrofluo-silicic acid on the large scale. The hydrofluosilicic acid was obtained by smelting silicic acid, fluorspar, and charcoal in a blast-furnace, and receiving in water the fluoride of silicon contained in the flue gases,t a process founded on the observations of Bredberg (1829) and Berthier (1835), and elaborated in its details by F. Bothe.t

Recently Christy and Bobrownicki|| have taken out a patent in England for obtaining ammonia from ammoniacal waters by means of hydrofluo-silicic acid. They precipitate the ammonia from such water by means of hydrofluo-silicic acid, and decompose the precipitate by means of quicklime without the application of heat. Whether this attempt to employ a siliceous compound in extensive chemical operations will meet with a better fate than its predecessors time alone must decide. It is the first mention of fluorine in chemical technological literature for the last five or six years.

The applications of fluorides seem in fact to be dominated by some hostile influence. Even the use of hydrofluoric acid for etching on glass, which appeared secure from rivalry, will probably experience considerable limitation in consequence of an American invention. B. C. Tilghmann§ uses for etching on glass and other brittle materials a jet of sand violently projected against the surface of the object by means of a current of air or of steam. (The details of this process are, of course, strictly mechanical.)

Against such a rival fluoric acid cannot possibly maintain its ground for etching, especially where large surfaces are concerned. It will be restricted to the production of fine delicate designs, such as the graduation of measuring instruments.

The Sulphur Industry of Sicily. Extracted from the Report of the Mining Engineer, LORENZO PARODI, ¶ by Dr. ANGELO BARBAGLIA, Professor of Chemistry at

the Instituto Tecnico of Rome.

Sulphur is a widely diffused element which occurs under the most various forms both in the free and the combined state. In a free condition it forms rich deposits, which may be divided into two classes; such as are found on the surface of the earth in the neighbourhood of extinct volcanoes (solfatare) forming earthy strata from 6 to 10 metres in thickness saturated with sulphur, and underground beds (solfare) in which the sulphur is so intimately

"Berichte über die Entwickelung der Chemischen Industrie Während des Letzten Jahrzehends."

+ Details concerning attempts at the industrial utilisation of hydrofuo-silicic acid will be found in the article on the compounds of silica. Bothe, Wagner Jahresber., 1868, 265.

Ber. Chem. Gesell., 1873, 1322.

B. C. Tilghmann. The sand-blast for cutting hard bodies. Sull estrazione dello solfo in Sicilia e sugli usi industriali del medesimo. Relazione dell ingegnére Lorenzo Parodi al Ministro d'agricultura, industria e commercia. Firenze, 1873.

233

intermingled with the sedimentary rock that it must be obtained by mining. The latter deposits are the more important and furnish nearly the whole of the sulphur of

commerce.

Geology. The most important sulphur deposits are those of Italy. On the main land are the beds of the Romagna, which yield yearly 120,000 quintals of sulphur those of Latera in the province of Viterbo, and those of Scrofano. Beds of sulphur have also been recently found in the provinces of Volterra, Grosseto, and Avellino. (To be continued.)

QUANTITATIVE ANALYSIS OF COAL AND PEAT.

By SERGIUS KERN, St. Petersburg.

The

SEVERAL analytical processes have been used by me for the estimation of carbon, hydrogen, ash, and sulphur in various coals, and most of them were found to be very accurate, but rather troublesome in execution. following process was used with great success and may be strongly recommended for laboratories of iron works, &c. By this process the work is easily and quickly executed, giving at the same time very accurate results.

1. Estimation of Hygroscopic Water.

3 grms. of the substance in a finely divided state are dried in a porcelain crucible placed in a beaker with a small quantity of sand on the bottom of it. The beaker is covered with a watch-glass, and the whole is placed on a sand-bath and heated for about three hours to a temknown by the dryness of the watch-glass. The substance The end of the operation is easily perature of 110°. when dried is weighed, and the percentage of loss is next

calculated.

2. Estimation of Carbon and Hydrogen. The best process was found to be Liebig's :-The ignition of 1 grm. of coal or peat with lead chromate (PbCrO4) in a tube of hard glass, o 25 metre long. The resulting carbonic acid, water, and sulphuric acid are passed through a potash apparatus containing caustic potash (1 part of KHO dissolved in 2 parts of H2O), and two U-tubes, the first containing ignited calcium chloride, the second a solution of lead nitrate. The increase in weight of the potash apparatus and of the first U-tube will show the quantity of carbonic acid and water obtained. Knowing that carbonic acid contains 27.2 per cent of carbon, and water 111 per cent of hydrogen, the percentage of carbon and hydrogen may be easily calculated. 3. Calculation of the Calorific Power.

As one part of carbon in burning yields 8080 calorific units, and I part of hydrogen in burning 34,460 calorific units, the calorific power of the coal may be quickly found. Example.-Coal from Donetz Mountains, near the village Grouchevka, South of Russia :

Per cent. 58.0

II'O

..

ΙΟ

23.0 6'0

99'0

234

4. Estimation of Ash.

I grm. of powdered coal is heated in a muffle in an open platinum dish till all the carbon is burnt off. The remainder is the ash which is weighed.

5. Estimation of Sulphur.

o'5 grm. of powdered coal is heated with a mixture of 15 c.c. of HCl and 5 c.c. of HNO3 for about one hour, and next left for 12 to 15 hours on a sand-bath. The liquor is filtered on a strong double filter to prevent the coal-dust passing into the filtrate. The sulphur is precipitated from the filtrate by barium chloride. The solution is left quiet for half an hour and is next filtered; the precipitate of BaSO4 is washed, dried, and then weighed. Supposing o'5 grm. of coal to be used for the analysis, every 0.001 grm. of barium sulphate obtained is equal to o'02 per cent of sulphur.

Obouchoff Steel Works, St. Petersburg.

PROCEEDINGS OF SOCIETIES.

CHEMICAL NEWS, Dec. 1, 1876.

upon this question will be best seen by tabulating the results so as to bring together the quantities of lead dissolved by the same liquid acting on a fixed surface, but under varying conditions of exposure to air.

This is done in Table II.

I have not tabulated the whole of the results here, but only those which are directly comparable with one another.

an

6. It is scarcely admissible from these experiments to conclude that exposure to air invariably causes increase in the quantity of lead dissolved. As in the consideration of the influence of surface exposed, it was found to be difficult, if not impossible, to eliminate other circumstances which modified the action, so here we appear to have many conditions tending to overshadow the effects of that one which it was especially desired to study. If we compare the quantities of lead dissolved in corked flasks and in open beakers, the action appears to be greater in the former than in the latter cases, until we come to deal with actions allowed to proceed during considerable periods of time, and upon somewhat extended surfaces of lead. When the surface exposed extended to 50 sq. cm. (to 500 cbc. of liquid) and the time of action amounted to 300 to 500 hours, the exposure of the surface

SOCIETY.

increased the quantity of lead dissolved in a given time. In these experiments the surface of liquid exposed to the air was increased from about 2 to about 100 sq. cm.

or beakers and in open basins we find that there is inBy comparing the quantities of lead dissolved in flasks variably a very marked increase in the latter cases. The

increase here also becomes more marked when the action has been allowed to proceed for tolerably extended periods of time.

In these experiments the surface of liquid exposed to the action of air increased from about 2 to about 170 sq.cm.

Description of Vessel.

Surface of Lead.

Hours.

42

168 336 340 505 I'2 I'5

Flask

0'4

0.5 0.8

2'0 4'2

through

Flask Beaker Basin

25

0'7

2.8 3.5

in air

Flask Beaker

Basin

Flask with air

pended in air

Flask

Beaker

Basin

Flask with air

Beaker-lead partly in air

Beaker-lead partly sus

pended in liquid, partly

G.-Potassium Carbonate, o'20 grm. per Litre.

H.-Potassium Carbonate, 0'20 grm. per Litre.

Beaker-lead partly sus

I.-Ammonium Sulphate, o 20 grm. per Litre.

J.-Ammonium Sulphate, o 20 grm. per Litre.

Flask

Beaker

great improvement. The authors of the report before us remark:-"The elevated air is more impure when the stratum of diffused chimney exhalations is reached, than it is below. The Londoner does not experience any great sense of purity of air from the top of St. Paul's as a general rule; and the haze of any large city is perceptible for miles on a still day—the entire city is covered as with a blanket by an ascending and dispersing cloud, and receiving its fresh air from beneath from all sides." In the American Capitol the air is drawn from the level of an elevated terrace, some 30 feet wide and 35 feet in height, beyond which lies a park, 800 to 1000 feet in width, carefully drained, and, as a matter of course, free from nuisances. A more favourable locality for drawing a supply of pure air could not well be selected. But when a proper source of fresh air has been found its introduction into the room involves two questions which may lead to four different systems. Are we to adopt the " "vacuum or the "plenum" method? In other words, are we to draw the foul air out or to force the fresh air in? A little consideration will show that the latter or plenum method is decidedly preferable. If we suck out the foul air, other air will stream in to supply its place, not merely from our carefully selected source of a supply, but from every conceivable quarter. We shall suck in "ground gases" from the soil beneath and through the foundations. The next question is whether we are to introduce pure air from above or from below? If we select the former method our descending stream of pure air meets the stream of contaminated air arising from the persons of the occupants, and the latter current, instead of being withdrawn as quickly and quietly as possible, is beaten back upon the inmates, and runs a great risk of being inhaled over again. The method actually adopted in the Hall of Representatives is the plenum from below. As a matter of course the temperature of the in-flowing current requires to be regulated. By means of a system of steam-pipes it is kept at the uniform heat of 70° F., which is found most conducive to the comfort of those present in the building. The fresh air enters through vertical gratings in the steps of the platforms, upon which the seats of the members are placed. The reason why horizontal gratings in the floor were not adopted is somewhat singular.

"The nearest approach to a uniform distribution would of course have been attained by the perforated floor and porous carpet of the House of Lords, England, but the habits of our people in use of tobacco put this method out of the question."

We learn from the Appendices that the arrangements for the ventilation of the Hall of Representatives, though originally well designed and efficient, have not been in all points maintained in thorough working order. The best systems in ventilation, as in everything else, are of little avail unless they are carefully attended to. The authors conclude with a significant reflection:-"The truth is, all our heating and ventilating appliances are a compromise of conditions-a truth extending beyond all mechanical operations to the phenomena of nature herself." On this we may all meditate with advantage.

CHEMICAL NEWS, Dec. 1, 1876.

and the summer term to the organic department. There is a "chemical colloquium" of one hour weekly, for the purpose of impressing the more important points of pure chemistry upon the students. Dr. Classen gives instructions in analytical chemistry two hours weekly, and the analytical department of the laboratory is open daily, except Saturday, for seven hours, under the superintendence of Prof. Landolt, and Drs. Classen, Brühl, and Clören. Prof. Stahlschmidt gives weekly four hours' instruction in technological chemistry, and four hours in the construction and arrangement of chemical manufactories, and, with his assistants Drs. Böckmann and Scheele, superintends practical work in the technological laboratory daily, except Saturday. Dr. Brühl lectures twice weekly in the summer term on theoretical chemistry. Dr. Landolt gives practical instructions in saccharimetry. Dr. Classen gives, in the summer time, one lecture weekly, on chemical jurisprudence and toxicology, and in the winter term on the determination of the illuminating power of gas and its technological analysis. Prof. Stahlschmidt lectures weekly on brewing and on the manufacture of beet-root sugar. Dr. Böckmann delivers two lectures weekly on dyeing and calico-printing, and two on stachiometry. In addition to all these facilities the students have the opportunity of visiting different chemical works in the surrounding country. We commend these complete and thoroughgoing arrangements to the careful consideration of the authorities of our new colleges in Leeds, Newcastle, Birmingham, and Bristol.

CORRESPONDENCE.

ANTHRACENE PRODUCTION.

To the Editor of the Chemical News. SIR,-In your journal of the 17th inst. is published an article on "Anthracene Production," by Dr. Frederick Versmann, in which the balance-sheet of the Chemische Industrie Actien Gesellschaft of Elberfeld, as recently pub. lished, is referred to in the following manner :

"In Germany al public companies are very properly compelled by law to publish their annual balance-sheet in at least three newspapers, and such document-published only on the 10th inst., in the Cologne Gazette-by the Chemische Industrie Actien Gesellschaft zu Elberfeld,' formerly Gessert Brothers, tells its own tale in a few figures. This official document informs the shareholders that the loss of the twelve months' working, dismal statement is merely a repetition of previous equally ending at Midsummer last, amounts to £40,000; and as this unsatisfactory balance-sheets, there seems to be little doubt that at next month's general meeting the Company will be wound up, and that very likely the whole capitalamounting to some £180,000-will be lost."

By request of the Chemische Industrie Actien Gesell schaft of Elberfeld we now beg to hand you a true copy of the said balance-sheet, from which you will see that the figures given by Dr. Versmann are inaccurate and his observations most unjustifiable.

this amount is the actual loss during the past three years, The profit and loss account is debtor about £40,000, but and not during one year. The capital of the company is £150,000, not £180,000.

Dr. Versmann takes upon himself to say that at the next general meeting of the company "very likely the whole of the capital will be lost."

As Dr. Versmann bases his remarks upon the figures given in the balance-sheet, we refer you to that document, which describes the position of the company on June 30,

nischen Schule.