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To the Edtior of the Chemical News. SIR,-Referring to a letter which appeared in the CHEMICAL NEWS (vol. xxxiv., p. 151), signed by Mr. Wanklyn, we ask your permission to make a short statement as follows:We beg to say that we are members of the Committee of Publication of the Analyst; that we consider we have devoted a fair amount of attention to our duties; that we have no wish to shirk our responsibility for anything that has appeared in the Analyst; and consequently we are in a position to deny as we hereby emphatically do Mr. Wanklyn's assertion that two other members of the Committee of Publication "alone are responsible for the contents of the paper."

Whatever may be Mr. Wanklyn's view of the duty of anyone holding office, we for ourselves can say that unless we felt ourselves both able and willing to perform our share of the duties of the Publication Committee of the Analyst we would certainly not allow our names to be published as members of that committee.-We are, &c., CHAS. HEISCH. A. DUPRE.

October 9, 1876.

BLOWPIPE ANALYSIS OF THE NEW MINERAL

HENWOODite.

To the Editor of the Chemical News.

It was taught to every student at Freiberg, and I have seen it used very frequently there and elsewhere. It is certainly new to use oxide of lead for the test, the usual method being to fuse the mineral with a piece of metallic lead. The use of oxide serves no good purpose, and has no object whatever; it only increases very unnecessarily the "great effervescence" of which Major Ross speaks. It is quite correct of Major Ross to state that the test is best seen with Libethenite; and if he will look under that mineral in Dana's "Mineralogy" he will find the reaction fully described.-I am, &c., H. M. W.

HENWOODITE.

To the Editor of the Chemical News. SIR,-Allow me to write a few lines in reply to Major Ross's remarks on my blowpipe experiments with Henwoodite. He says that by the methods I employed "the iron present is not detected at all." The reason I did not find any iron is simply this-there was probably none present. I took great care to use very pure fragments of the mineral, examining each one minutely with a lens before testing it; and my friend Mr. J. H. Collins informs me that when he tested some pure specimens with sulphocyanide of potassium, he was unable to detect the presence of iron. Major Ross admits that his specimens, even after his beginning to test them, were mixed with Göthite (? Limonite), and I cannot help surmising that the iron he detected was simply a mechanical impurity. Had there been much iron present I should not have obtained a blue bead with borax (cold). Besides, the precipitate with ammonia would have revealed its presence.

I cannot lay claim to the "great sagacity" with which Major Ross credits me for suspecting the presence of P205 in Henwoodite. The association of that mineral with Chalkosiderite, a hydrated phosphate of iron and copper, and its globular form, would naturally lead any mineralogist to test for phosphoric acid.

One word more :-Major Ross's "new test for cupric phosphate " seems to me to be merely a modification of Berzelius's good old method, which has been known for more than fifty years. Berzelius used metallic lead, which is found in every complete blowpipe case, whilst Major Ross employs the oxide. The new method requires an additional, and it appears to me unnecessary, reagent.

In conclusion, let me assure you that I would not on any account undervalue Major Ross's labours; on the contrary, I congratulate him on having discovered many new and original tests in the too much neglected art of blowpipe analysis.—I am, &c.,

Truro, October 16, 1876.

CLEMENT LE NEVE FOSTER.

SOURCES.

66

(6.) Heated another piece of (1), with pure oxide of lead, on a charcoal mortar on aluminium plate. Fused with great effervescence to a crystalline mass of plumbic phosphate, with minute balls of copper interspersed. (This new test for cupric phosphate is best seen with Libethenite: the copper disengaged seems beautifully pure)."

This is a very interesting and characteristic reaction, but it is most certainly not new, as Major Ross asserts it to be. On the contrary, it is very old, and very well known to everybody who has practised the use of the blowpipe to any extent. If Major Ross will obtain a copy of Plattner's book on the Blowpipe, he will find the test fully described (the copy now before me is the German edition of 1865), and learn that it was given first by Berzelius.

NOTE.-All degrees of temperature are Centigrade, unless otherwise

expressed.

Comptes Rendus Hebdomadaires des Seances, de l'Acadenie des Sciences. No. 13, September 25, 1876. Probable Consequences of the Mechanical Theory of Heat.-M. Le Général Favé.-The substance which fills space, and which we call ether, without knowing whether it is simple or multiple, transmits the solar heat to the planets. This heat is a vibratory movement which the ether communicates to ponderable matter, and which has a speed of translation so considerable that we may ask if the heat coming from the sun does not exert a re.

* Berzelius, "Anwendung des Löthrohrs," p. 164. Nümberg, 1821.

174

CHEMICAL NEWS Oct. 20, 1876.

On Aniline-Black.-M. R. Nietzki.-The aniline used as material was prepared from crystallised benzol; it had a constant boiling-point (182), and yielded no magenta when treated with chloride of mercury. The aniline-black was prepared by Müller's method :-A mixture of 20 grms. chlorate of potassa was heated with 30 grms. sulphate of copper, 16 grms. sal ammoniac, and 40 grms. hydrochlorate of aniline dissolved in 500 c.c. of water. Vapours escape, having the odour of chloropicrin, and the solution is converted into a greenish black paste. The vapours are not perceived when a salt of aniline is employed which has been purified by re-crystallisation, whence the author con. cludes that their origin is due to the presence of traces of nitrobenzol. The product of the reaction is boiled with dilute hydrochloric acid, dried, ground up, and treated with benzol, ether, petroleum, and alcohol; or it is preferably boiled with acidulated alcohol, which dissolves a large quantity of brown matter. There remains a dark green powder, which M. Reineck considers as the hydrochlorate of a base which he proposes to name nigranilin. Aniline-black dissolves in sulphuric acid with a violet colour, and is precipitated from this solution on the addition of water as a sulphate. Coquillion obtained anilineblack by the electrolysis of a salt of aniline, and R. Meyer by the action of permanganate of potassa. The author attempted to purify aniline-black by solution in concentrated sulphuric acid, but this method cannot be employed because the solution filters very slowly, and the product thus treated leaves on combustion a large quantity of ash. It is preferable to dissolve aniline-black in aniline, and then neutralise with hydrochloric acid, which throws down the colouring matter, but the yield is very trifling, as a large proportion remains in solution. The author concludes that aniline-black is the mono-acid hydrochlorate of a triamin, having the formula C18H15N3HCl, and is composed of

County Analyst for Cheshire.-On Monday last Mr. J. Carter Bell, Public Analyst for Salford, was elected by a large majority to be the County Analyst for Cheshire. The Monthly Reports of the Department of Agricul ture. The reports for May and June, 1876, issued from the Government Printing Office, Washington, contain a notice of the Centennial Exhibits of the Department of Agriculture. One feature of these, though nowise chemical in its nature, claims brief notice on account of its importance and novelty of arrangement. It is a collection of destructive insects, arranged, not according to their scientific classification, but according to the fruits, farm produce, &c., which they injure or destroy. "Thus under the head of potato,' the various insects known to injure the plant in root, stalk, leaf, or fruit are shown from egg to perfect insect, when practicable, accompanied with samples illustrating the mode of injury. Other cases illustrate the insect pests of man and cattle, the foes of the household, and the larder, whilst others show the principal insects beneficial to mankind either by destroy

manures.

imity are shown the birds that are either injurious or beneficial. "The character of the birds is indicated in each case by the mark upon the perch or label; white indicating purely insectivorous birds, black those of wholly pernicious habits, and both colours the relative proportion of each element in these possessing more or less marked proclivities for a mixed diet. A little box in close juxtaposition to each affords the means of judging of these characteristics by an exhibit of the dried contents of a full stomach." Would not such a collection form a very useful feature in the economic museums of our country? of the fungi commonly known as "molds," so destructive The microscopic exhibits comprise highly magnified views to vegetation. The chemical department embraces an extensive assortment of rocks, with samples of the soils formed by their disintegration and decomposition of marls, mineral manures, such as phosphatic rocks and limestones, and of vegetable, animal, and compound Another grand series shows useful agricultural and horticultural products and their preparations. Such is to be hoped will not be dispersed when the Centennial collections are evidently of great permanent value and it Exhibition is at an end. The Report for July contains notices of the steps taken in Spain for the destruction of locusts and for promoting the growth of forests. Locusts, it is found, like most other insect-plagues, are always most plentiful in dry, open, treeless wastes, land of the very class in which Spain is now so rich. There is an interesting article on the cultivation of coffee in Mexico and also in Brazil, and a variety of agricultural notices from many parts of the world. The Report for August and September is chiefly filled up with very complete returns of the condition of the principal crops throughout the United States. The agricultural interests of America are judiciously watched over by the Government, which, without any attempt at vexatious interference, collects and distributes valuable information, and what is equally important, puts it in a clearly intelligible form. It would certainly be beneficial to our agriculturists if monthly reports like the one before us were circulated amongst them. Forest-planting, strange as it may sound to those who conceive of America as it was a hundred years ago, is strongly and wisely advocated. The usual complaints about insect pests are not wanting. This evil is a necessary result of the system of gigantic fields without hedge-rows and trees, and consequently devoid of shelter for the small birds. Some interesting climatological facts deserve attention. Thus in Georgia the apples were mostly destroyed by a frost in April, although the district corresponds in latitude to the delta of the Nile.

NOTES AND QUERIES.

Our Notes and Queries column was opened for the purpose of giving and obtaining information likely to be of use to our readers generally. We cannot undertake to let this column be the means of transmitting merely private information, or such trade notices as should legitimately come in the advertising columns. good work on the technical analysis of animal charcoal.-T. W. I. Animal Charcoal.-Will any of your readers kindly refer me to a

Separation of Arsenic and Copper.-In answer to query concerning separation of arsenic and copper, I may say that I have experienced the same difficulty myself, and it is, I think, a very likely one for persons who have not practised long. I think it is from a fear of having too much alkaline sulphide in the solution that it arises. I may say too that I have found a little of either caustic soda or potash in the ammonium or other sulphide to be beneficial when copper and arsenic only have to be separated.-WM. ELLSTONE. give me the name and address of the society or English scientific academy which has offered a prize to the inventor of an agent which will actually preserve iron from the oxidising action of the saline matter in the air of the Antilles, and especially from the aggregation of molluscs and shell-fish on the iron, wood, or stone action of salt-water, and which will at the same time prevent the which are plunged into such waters.-A.

Preservation of Iron from Action of Salt. Can you

87. With a large bulb, very well exhausted and containing a suspended bar of pith, a somewhat striking effect is produced when a lighted candle or other radiant source is brought about 2 inches from the globe. The pith bar commences to oscillate to and fro, the swing gradually increasing in amplitude until the dead centre is passed over, and then several complete revolutions are made. The torsion of the suspending fibre now offers resistance to the revolutions, and the index commences to turn in the opposite direction. This movement is kept up with great energy and regularity as long as the candle burnsproducing, in fact, perpetual motion, provided only the radiation falling on the pith be perpetual.+ If the candle is brought closer to the bulb, the rotation of the pith becomes more rapid; if it is moved further away the pith ceases to pass the dead centre, and at a still further distance the index sets equatorially. The explanation of the different movements of the pith index according to the distance the radiant body is off, is not difficult on the supposition that the movement is due to the direct impact of waves on the suspended body.

88. It is not at first sight obvious how ice, or a cold substance, can produce the opposite effect to heat, cold being simply negative heat (33). The law of exchanges, however, explains this perfectly. The pith index and the whole of the surrounding bodies are incessantly exchanging heat-rays; and under ordinary circumstances the income and expenditure of heat are in equilibrium. A piece of ice brought near one end of the index cuts off the influx of heat to it from that side, and therefore allows an excess of heat to fall upon it from the opposite side. Attraction by a cold body is therefore seen to be only repulsion by the radiation from the opposite side of the room.

Bearing the law of exchanges in mind, several apparent anomalies in the movements of these indices are cleared up; and it is also easy to foresee what the movement of a body will be when free to move in space under the inAuence of varying amounts of radiation.

The heat which all bodies radiate into space can have no influence in moving them, except there be something in the nature of a recoil in the act of emitting radiation. And even should there be such a recoil, if the body radiates heat equally all round, the recoil will be uniform, and will not move the body in one direction more than in another. I need therefore only consider the effect of the radiation received by a body. Here also the influx of radiation to a body free to move in space of a uniform temperature may be considered to be equal, and it will acquire the temperature of space without moving in any direction.

89. The case is, however, different if two bodies, each free to move, are near each other in space, and if they differ in temperature either from each other or from the limiting walls of the space. I will give here four typical cases, with experiments sufficient to prove the reasoning to be correct.

uniformly from space, except where the body B intervenes ; and on this side A receives more heat, as B is hotter than the space behind it; A will therefore move from B. In the same manner it can be shown that B will move from A. The result will therefore be mutual repulsion.

FIG. 2.

Case I.

CASE II. Two cold bodies, A and B, in space of a higher temperature than themselves. A will receive much heat from space, except where B cuts it off, and on that side it will only receive slight radiation from B. A will therefore be driven towards B. In the same manner it can be shown that B will be driven towards A; and the result will therefore be an apparent mutual attraction.

CASE III. Two bodies, A hot and B cold, in cold space. The body A receives heat uniformly from all sides, even from that opposite B (B being of the same temperature as space). A will therefore not move. B receives heat uniformly from all sides, except from that opposite A, on which side the influx of heat is more intense. The result will therefore be that A remains stationary whilst B is repelled.

CASE IV. Two bodies, A hot and B cold, in hot space. The body A receives heat uniformly from all sides, except from that opposite B. Here the heat is less intense. A is therefore driven towards B by the extra influx of heat on the other side of A. B receives strong influx of heat from all sides, and just as much from the side opposite A as from any other. B will therefore not move. The result will be that A will be apparently attracted towards B, whilst B will remain stationary.

The force with which the bodies A and B in these four

176

CHEMICAL NEWS,

To be continued.)

ON THE ACTION OF DIFFERENT FATTY OILS UPON METALLIC COPPER.*

By WILLIAM THOMSON, F.R.S.E., F.C.S.

WITH the view to study the actions of different fatty oils upon copper I made two series of experiments. In the first, which was commenced on the 1st October, 1875, I took twenty-six different samples and measured 150 grs. of each into bottles; into each bottle was then placed a piece of copper foil, 1 inch long by inch broad, so as to lie flat at the bottom of the oil. After a few days it was observed that some of the samples had acted on the pieces of copper, some had thrown on to the metallic surface a slight greenish incrustation, some had produced a dark coloured incrustation, and the remainder produced no effect on the bright metallic surface of the copper.

No special examination of either the metallic copper or the oils was made till they had remained in contact for ten months at the ordinary temperatures of the atmosphere.

* Read before the British Association, Glasgow Meeting (Section B.).

The second series was commenced about one month later than the first, and differs from the first somewhat in the detail of its arrangement. Eighteen different samples were employed, each oil representing in both series a distinct and different sample, although in some cases two or more of the same kind of oil were employed, and I am indebted to the kindness of Mr. Wollaston, of Manchester, for the greater number of the samples used in both series and for the care which he exercised in obtaining samples which could be relied upon as being free from adulteration.

In this second series 300 grs. of each sample were placed in bottles, and a slip of well-cleaned metallic copper, 3 inches long by inch broad, put into each so that only one half of the slips was immersed in the oil, whilst the other half was exposed to the air. The following is a list of the different samples used :— IN SECOND Series. Vegetable Oils.

IN FIRST SERIES.
Vegetable Oils.

1. Mesina olive oil.

2. Olive oil.

3. Rape oil.

4. Refined rape oil. 5. Cotton seed oil.

6. Pale cotton seed oil.

7. Cotton seed oil. 8. Linseed oil. 9. Almond oil. 10. Palm oil.

Animal Oils.

1. Olive oil.

All these samples of oil, together with the slips of metallic copper left in contact with them, were examined on the 9th of August, 1876, in the following manner :First.-Each slip of copper was carefully examined and its appearance noted.

Second. The appearance of each oil was observed and noted.

Third.-Ten grains of each sample were measured off by a pipette and placed in a small test-glass, and 5 grs. of a moderately strong solution of ferrocyanide of potassium added, and the oil and solution thoroughly mixed by stirring them together for some time and then leaving them for about a day. This method I found to give the most satisfactory result for testing the relative proportions of copper which had been dissolved by the oils; the characteristic brownish red precipitate of ferrocyanide of copper being thrown down admitted of very accurate comparison.

Fourth.-Fifteen grains of each oil were taken by means of a pipette, and each placed in a small stoppered test-tube; 15 grs. of distilled water were then added and each tube shaken violently. The tubes were then suspended in water and heated to about 200° F. and shaken violently two more times at intervals of one hour each, and allowed to remain in contact with the hot water at 200° F. for six hours; the source of heat was then removed and the oils allowed to remain over the night to allow the water to separate from the oils more completely.