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CHEMICAL News, 172 Blowpipe Analysis of Henwoodite.
Oct. 20, 1876. the coloured compound is a lime-salt of ferric acid : this, It was taught to every student at Freiberg, and I have would account for the appearance of the colour where seen it used very frequently there and elsewhere. It is Deacon's process for the preparation of chlorine is used, certainly new to use oxide of lead for the test, the usual since traces of iron could hardly be excluded from any method being to fuse the mineral with a piece of metallic process of chlorine manufacture.
lead. The use of oxide serves no good purpose, and has It is to be noted that no colour is produced where the no object whatever; it only increases very unnecessarily "chloride” is exhausted with cold water; a temperature the "great effervescence” of which Major Ross speaks. at or near the boiling-point is necessary to the appearance
It is quite correct of Major Ross to state that the test of the phenomenon.-I am, &c.,
is best seen with Libethenite ; and if he will look under Thos. P. BLUNT, M.A. Oxon., F.C.S.
that mineral in Dana’s “ Mineralogy” he will find the re
action fully described.—I am, &c., Tower Place, Shrewsbury,
H. M. W. October 3, 1876.
DETERMINATION OF GOLD IN PYRITES.
To the Editor of the Chemical News. Sır,—In reply to “ Assayer" on the above subject, I did / Sir,-Allow me to write a few lines in reply to Major not propose iron turnings myself, but simply gave the most Ross's remarks on my blowpipe experiments with Henconvenient method for obtaining the gold from the mineral, woodite. He says that by the methods I employed "the as it had then been treated. And now, as “ Assayer" iron present is not detected at all.” The reason I did not will perceive, the deoxidising process still holds good in find any iron is simply this—there was probably none preall cases.-I am, &c.,
sent. I took great care to use very pure fragments of the LATENT. mineral, examining each one minutely with
a lens before October 9, 1876.
testing it; and my friend Mr. J. H. Collins informs me that when he tested some pure specimens with sulpho
cyanide of potassium, he was unable to detect the presence PROF. DITTMAR AND THE "ANALYST."
of iron. Major Ross admits that his specimens, even
after his beginning to test them, were mixed with Göthite To the Edtior of the Chemical News.
(? Limonite), and I cannot help surmising that the iron he SIR, -Referring to a letter which appeared in the CHEMICAL detected was simply a mechanical impurity. Had there News (vol. xxxiv., p. 151), signed by Mr. Wanklyn, we been much iron present I should not have obtained a blue ask your permission to make a short statement as follows :- bead with borax (cold). Besides, the precipitate with We beg to say that we are members of the Committee of ammonia would have revealed its presence. Publication of the Analyst ; that we consider we have I cannot lay claim to the “ great sagacity” with which devoted a fair amount of attention to our duties; that we Major Ross credits me for suspecting the presence of have ro wish to shirk our responsibility for anything that P2O5 in Henwoodite. The association of that mineral has appeared in the Analyst ; and consequently we are in with Chalkosiderite, a hydrated phosphate of iron and a position to deny—as we hereby emphatically do-Mr.copper, and its globular form, would
'naturally lead any Wanklyn's assertion that two other members of the Com- mineralogist to test for phosphoric acid. mittee of Publication " alone are responsible for the con- One word more :-Major Ross's " new test for cupric tents of the paper."
phosphate " seems to me to be merely a modification of Whatever may be Mr. Wanklyn's view of the duty of Berzelius's good old method, which has been known for anyone holding office, we for ourselves can say that unless
more than fifty years.* Berzelius used metallic lead, we felt ourselves both able and willing to perform our which is found in every complete blowpipe case, whilst share of the duties of the Publication Committee of the Major Ross employs the oxide. The new method requires Analyst we would certainly not allow our names to be an additional, and it appears to me unnecessary, reagent. published as members of that committee. We are, &c., In conclusion, let me assure you that I would not on
CHAS. HEISCH. any account undervalue Major Ross's labours ; on the
A. DUPRE. contrary, I congratulate him on having discovered many October 9, 1876.
new and original tests in the too much neglected art of blowpipe analysis.-I am, &c.,
CLEMENT Le Neve FOSTER. BLOWPIPE ANALYSIS OF THE NEW MINERAL
Truro, October 16, 1876.
To the Editor of the Chemical News. Sır, -- Under the above heading (Chem. News, vol. xxxiv., CHEMICAL NOTICES FROM FOREIGN p. 156) Major Ross gives an account of his examination,
SOURCES. by his new methods, of Henwoodite. The following passage occurs in his article:
" (6.) Heated another piece of (1), with pure oxide of Note.-A11 degrees of temperature are Centigrade, unless otherwise lead, on a charcoal mortar on aluminium plate. Fused
expressed. with great effervescence to a crystalline mass of plumbic phosphate, with minute balls of copper interspersed. Comptes Rendus Hebdomadaires des Seances, de l'Acadenie (This new test for cupric phosphate is best seen with
des Sciences. No. 13, September 25, 1876. Libethenite : the copper disengaged seems beautifully Probable Consequences of the Mechanical Theory pure)."
of Heat.-M. Le Général Favé.-The substance which This is a very interesting and characteristic reaction, but fills space, and which we call ether, without knowing it is most certainly not new, as Major Ross asserts it to whether it is simple or multiple, transmits the solar heat be. On the contrary, it is very old, and very well known to the planets. This heat is a vibratory movement which to everybody who has practised the use of the blowpipe to the ether communicates to ponderable matter, and which any extent. If Major Ross will obtain a copy of Platt. has a speed of translation so considerable that we may ner's book on the Blowpipe, he will find the test fully I ask if the heat coming from the sun does not exert a re. described (the copy now before me is the German edition of 1865), and learn that it was given first by Berzelius. I * Berzelius, " Anwendung des Löthrohrs,” p. 164. Nümberg, 1821.
173 pulsive force upon each planet. Transparent bodies are chlorine, and diluted with an equal volume of water. traversed by radiant heat in a greater or less degree. After washing it may be regarded as pure. That is, the vibratory movements of the ether intercommunicate in the whole interior of the transparent Moniteur Scientifique, du Dr. Quesneville, body without being transmitted, at least directly to the
September, 1876. ponderable matter. Thus, transparent bodies are constituted with ether interposed in their interstices. It is Schunck and H. Rømer.—These authors have announced
Anthraflavic and Iso-anthraflavic Acids.-MM. E. known that a body which has passed from the solid to the in an earlier memoir the discovery of an acid isomeric liquid state, or from the liquid to the gaseous, has absorbed with the anthraflavic, to which they have given the name latent heat, and yet the molecules doubtless have not
of isoanthraflavic acid, and which is prepared as follows: changed their vibratory speed when the solid, liquid, or gas have been brought to the same temperature. What, The crude material prepared by Mr. Perkin is obtained on then, is the latent heat, that is to say, the movement in precipitating with hydrochloric acid a solution derived sensible to the indications of the thermometer ? We from the treatment of crude alizarin with lime-water. It believe that everything, may be explained; that the liquid precipitate in dilute soda-lye: the filtrate yields, on the
is first separated from anthraquinon by dissolving the contains, to a larger degree than the solid, interposed addition of hydrochloric acid, a yellow precipitate, which ether, which vibrates in unison with the ponderable matter. is partly dissolved in cold baryta-water. The blood-red On this hypothesis, the gas would contain yet more constitutive ether than the liquid. The transparence of
solution is precipitated by acids in green flocks, turning
red. liquids, and the facility with which gases give passage to alcohol, gives a substance which forms yellow needles, and
This precipitate, if repeatedly crystallised from radiant heat, are facts favourable to this explanation.
which, if dried at 150°, yields on analysis the following Photo-micrographic Researches on the Effects of results :the Reduction of Salts of Silver in Photographic
Calculated for Proofs.-M. J. Girard.-On examining under a strong
69.79 magnifying power a negative proof developed indistinctly
H with sulphate of iron or pyrogallic acid, we remark almost
3:33 invariably in the light portions not acted upon, crystals Isoanthraflavic acid crystallises with water; a portion uniformly disseminated, scarcely 1-100 of a m.m. in size. evaporates on desiccation over sulphuric acid, but the These crystals of reduced iodide of silver, sometimes very crystals preserve their lustre unless heated to 120°. The abundant, are the cause of frequent failures, as they form authors have also analysed the barium salt which corres. a cloud impervious to light.
ponds to the formula C14H6Ba04. New Process for the Extraction of Gallium.-M. baryta-water (see above) is composed of anthraflavic acid.
Anthraflavic Acid. — The portion insoluble in cold Lecoq de Boisbaudran.---The ore, according to its nature, The barium salt of this acid closely resembles the corresis dissolved in aqua regia, hydrochloric or sulphuric acid. The cold liquid is treated with plates of zinc, and filtered, ponding salt of isoanthraflavic acid, but it is insoluble. It when the escape of hydrogen is still considerable. The crystallises with two molecules of water, and is gradually liquid is then heated with a large excess of zinc. The decomposed on exposure to the air. gelatinous deposit is washed, and redissolved in hydro- Properties of Isoanthraflavic and Anthraflavic Acids, chloric acid. The new liquid is heated with an excess of
Anthraflavic Acid, zinc, and a second gelatinous precipitate is obtained. Into
Crystallises from aqueous the hydrochloric solution of this second precipitate formed
Crystallises without water.
alcohol with by zinc a current of sulphuretted hydrogen is passed, the
crystalline liquid is filtered, the excess of sulphuretted hydrogen driven off, and it is fractionated with carbonate of soda,
Melting-point above 330°. Ditto.
Less soluble in glacial Ditto. ceasing when the ray Gaa 417'0 ceases to be visible with the hydrochloric solution of the precipitate. The oxides acetic acid than in alcohol.
Almost insoluble in ben- Ditto. or sub-salts are taken up with sulphuric acid; the solu. tion is carefully evaporated until white sulphuric acid zol, chloroform, and ether.
Soluble in concentrated vapours are no longer, or but slightly, given off
. It is let trated sulphuric acid with sulphuric acid with a yellow. cool, and stirred with water, which dissolves the mass after the lapse of a time varying from some hours to a
a deep red.
Easily soluble in cold Insoluble in cold baryta. couple of days. The solution of the sulphate almost neutral is diluted with much water, and raised to a boil.
water. The sub-salt of gallium is separated by filtration whilst
Easily soluble in lime- Soluble with difficulty in hot. This basic salt is dissolved in a little sulphuric acid,
cold lime-water, and less
soluble at a boil, and the liquid is mixed with a slight excess of caustic
Carbonic acid throws Ditto. potassa, so as not (?) to dissolve the galliuna, but to leave the iron. It is filtered, and the oxide of gallium is pre. the aqueous solution of the
down anthraflavic acid from cipitated by a prolonged current of carbonic acid. This barium salt, but the salt is oxide is re-dissolved in a minimum of sulphuric acid, a slight excess of acetate of ammonia, feebly acid, is added, re-formed on ebullition.
Soluble in alcoholic lead Ditto. and it is then treated with sulphuretted hydrogen. Under
acetate. these conditions the gallium is not precipitated. The
The solutions in alkalies The solutions in alkalies acetic liquid is filtered, diluted with water, and raised to a boil. The bulk of the gallium is precipitated and filtered and alkaline earths are of an and alkaline earths are more whilst hot. The mother-liquor, concentrated, and boiled intense red.
or less tinged with reddish with aqua regia in order to destroy ammoniacal salts, is
yellow. added to the other gallium residues. The precipitate
Sublimes in brilliant yel- Ditto. formed on heating the acetic liquid is re-dissolved in sul. | low needles and leaflets. phuric acid, a slight excess of caustic potassa is added,
Is not fixed by mordants. Ditto. and it is then filtered. The potassic solution is electro- The authors have examined the tetrabromated isoanthralysed. The gallium is easily detached from the sheet of flavic acid, the corresponding anthraflavic compound, and platinum on pressing it between the fingers under warm the diacetylic, diethylic, and dimethylic derivatives of the water. The metal is then immersed for about half an two acids.-Berichte der Deutschen Chemischen Gesellschaft hour in nitric acid at about 60° or 709, quite free from su Berlin.
oa. 20, 1876. Easy Method of Preparing Condensed Hydro- | ing noxious species or as scavengers.” In close proxcarbides.-Watson Smith.-The author passes through imity are shown the birds that are either injurious or an ignited tube vapours of naphthalin mixed with tri- beneficial. “The character of the birds is indicated in chloride of antimony. Isodinaphthyl is obtained. each case by the mark upon the perch or label; white
Addition-Products of Aldehyd.-M. R. Schiff.—This indicating purely insectivorous birds, black those of wholly paper consists chiefly of hypothetical formulæ.
pernicious habits, and both colours the relative propor. On Aniline-Black.-M. R. Nietzki.—The aniline used tion of each element in these possessing more or less as material was prepared from crystallised benzol; it had marked proclivities for a mixed diet. A little box in close a constant boiling-point (182°), and yielded no magenta juxtaposition to each affords the means of judging of these when treated with
chloride of mercury. The aniline Black characteristics by an exhibit of the dried contents of a full was prepared by Müller's method :-A mixture of 20 grms: useful feature in the economic museums of our country?
stomach." Would not such a collection form a very chlorate of potassa was heated with 30 grms. sulphate of! The microscopic exhibits comprise highly magnified views copper, 16 grms. sal ammoniac, and 40 grms, hydrochlorate of the fungi commonly known as “molds,” so destruđive of aniline dissolved in 500 c.c. of water. Vapours escape, having the odour of chloropicrin, and the solution is con
to vegetation. The chemical department embraces an verted into a greenish black paste. The vapours are not
extensive assortment of rocks, with samples of the soils perceived when a salt of aniline is employed which has formed by their disintegration and decomposition of been purified by re-crystallisation, whence the author con marls, mineral manures, such as phosphatic rocks and cludes that their origin is due to the presence of traces of limestones, and of vegetable, animal, and compound nitrobenzol. The product of the reaction is boiled with
Another grand series shows useful agricultural dilute hydrochloric acid, dried, ground up, and treated and horticultural products and their preparations. Such with benzol, ether, petroleum, and alcohol; or it is pre: is to be hoped will not be dispersed when the Centennial
collections are evidently of great permanent value and i: ferably boiled with acidulated alcohol, which dissolves a large quantity of brown matter. There remains a dark Exhibition is at an end. The Report for July con. green powder, which M. Reineck considers as the hydro- tains
notices of the steps taken in Spain for the destrucchlorate of a base which he proposes to name nigranilin. tion of locusts and for promoting the growth of forests. Aniline-black dissolves in sulphuric acid with a violet Locusts, it is found, like most other insect-plagues, are colour, and is precipitated from this solution on the addi- always most plentiful in dry, open, treeless wastes, land of tion of water as a sulphate. Coquillion obtained aniline the very class in which Spain' is now so rich. There is black by the electrolysis of a salt of aniline, and R. Meyer an interesting article on the cultivation of coffee in by the action of permanganate of potassa. The author
Mexico and also in Brazil, and a variety of agricultural attempted to purify aniline-black by solution in concen
notices from many parts of the world. The Report for trated sulphuric acid, but this method cannot be employed August and September is chiefly filled up with very combecause the solution filters very slowly, and the product plete returns of the condition of the principal crops thus treated leaves on combustion a large quantity of ash throughout the United States. The agricultural interests It is preferable to dissolve aniline-black in aniline, and of America are judiciously watched over by the Governthen neutralise with hydrochloric acid, which throws down ment, which, without any attempt at vexatious interferthe colouring matter, but the yield is very trifling, as a
ence, collects and distributes valuable information, and large proportion remains in solution. The author concludes what is equally important, puts it in a clearly intelligible that aniline-black is the mono-acid hydrochlorate of a form. It would certainly be beneficial to our agricul. triamin, having the formula C18H15N3HCl, and is com
turists if monthly reports like the one before us were cirposed of,
culated amongst them. Forest-planting, strange as it с
may sound to those who conceive of America as it was H
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 IT'47
fields without hedge-rows and trees, and consequently Constitution of Naphthalin.-M. F. Wreden.-This devoid of shelter for the small birds. Some interesting paper consists of hypothetical formulæ.
climatological facts deserve attention. Thus in Georgia Titration and Assay of Salts of Soda.-M. A. Favre. 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 a large majority to be the County Analyst for Cheshire. giving and obtaining information likely to be of use to our readers The Monthly Reports of the Department of Agricul.
generally. We cannot undertake to let this column be the
means of transmitting merely private information, or such trade ture.—The reports for May and June, 1876, issued from notices as should legitimately come in the advertising columns. the Government Printing Office, Washington, contain a notice of the Centennial Exhibits of the Department of good work on the technical analysis of animal charcoal.-T. W. 1.
Animal Charcoal.-Will any of your readers kindly refer me to a Agriculture. One feature of these, though nowise che
Separation of Arsenic and Copper.-In answer to query conmical in its nature, claims brief notice on account of its cerning separation of arsenic and copper, I may say that I have eximportance and novelty of arrangement. It is a collection perienced the same difficulty myself, and it is, I think, a very likely of destructive insccts, arranged, not according to their
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 scientific classification, but according to the fruits, farm
may say too that I have found a little of either caustic soda or potash produce, &c., which they injure or destroy. “Thus under in the ammonium or other sulphide to be beneficial when copper the head of potato,' the various insects known to injure and arsenic only have to be separated.-WM. Ellstone. the plant in root, stalk, leaf, or fruit are shown from egg I give me the name and
address of the society of English scienti
Preservation of Iron from Action of Salt. - Can you to perfect insect, when practicable, accompanied with
fic academy which has offered a prize to the inventor of an samples illustrating the mode of injury. Other cases agent which will actually preserve iron from the oxidising action of illustrate the insect pests of man and cattle, the foes of the saline matter in the air of the Antilles, and especially from the the household, and the larder, whilst others show the action of salt-water, and which will at the same time prevent the principal insects beneficial to mankind either by destroy, which are plunged into such waters.-A.
aggregation of molluscs and shell-fish on the iron, wood, or stone CHEMICAL News,
Repulsion Resulting from Radiation. Oct. 27, 1876.
CASE I. Two hot bodies, A and B, in space of a lower THE CHEMICAL NEWS, temperature
than themselves. The body A receives heat uniformly from space, except where the body B intervenes ;
and on this side A receives more heat, as B is hotter than VOL. XXXIV. No. 883.
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.
ON REPULSION RESULTING FROM
By WILLIAM CROOKES, F.R.S., &c.
(Continued from p. 166).
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
B 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
Case II. 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 ofthe surrounding bodies are incessantly exchanging
B heat-says; 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 in- Case II. Two cold bodies, A and B, in space of a Auence of varying amounts of radiation. The heat which all bodies radiate into space can have higher temperature than themselves. A will receive much
heat from space, except where B cuts it oft, and on that no influence in moving them, except there be something side it will only receive slight radiation from B. A will in the nature of a recoil in the act of emitting radiation. therefore be driven towards B. In the same manner it And even should there be such a recoil, if the body radiates
can be shown that B will be driven towards A; and the heat equally all round, the recoil will be uniform, and will result will therefore be an apparent mutual attraction. not move the body in one direction more than in another.
Case III. Two bodies, A hot and B cold, in cold space. I need therefore only consider the effect of the radiation | The body A receives heat uniformly from all sides, even received by a body. Here also the influx of radiation to a
from that opposite B (B being of the same temperature as body free to move in space of a uniform temperature may space). A will therefore not move. B receives heat uni. be considered to be equal, and it will acquire the tempera- formly from all sides, except from that opposite A, on which ture of space without moving in any direction.
side the influx of heat is more intense. The result will 89. The case is, however, different if two bodies, each
therefore be that A remains stationary whilst B is repelled. free to move, are near each other in space, and if they Case IV. Two bodies, A hot and B cold, in hot space. differ in temperature either from each other or from the The body A receives heat uniformly from all sides, except limiting walls of the space.. I will give here four typical from that opposite B. Here the heat is less intense. A cases, with experiments sufficient to prove the reasoning is therefore driven towards B by the extra influx of heat to be correct.
on the other side of A. B receives strong influx of heat
from all sides, and just as much from the side opposite A * A Paper communicated to the Royal Society, March 20, 1875. as from any other. B will therefore not move. The result From the Philosophical Transactions of the Royal Society of London, will be that A will be apparently attracted towards B, vol. clxv., pt. 2.
+ This experiment was exhibited for the first time at the Royal whilst B will remain stationary, Society's Soirée, April 22, 1874.
The force with which the bodies A and B in these four
176 Action of Different Fatty Oils upon Metallic Copper.
oa. 37, 1876. cases will be repelled, or apparently attracted, will vary The second series was commenced about one month with their distance from each other, being stronger when later than the first, and differs from the first somewhat in they are close and weaker when they are far apart. The the detail of its arrangement. Eighteen different samples
were employed, each oil representing in both series a disFig. 2. Case III.
tinct and different sample, although in some cases two or more of the same kind of oil were employed, and I am indebted to tlie 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, 31 inches long by 4 inch broad, put into each so
that only one half of the slips was immersed in the oil, B
whilst the other half was exposed to the air.
IN SECOND SERIES.
Vegetable Oils. 1. Mesina olive oil.
1. Olive oil,
3. Pale rape oil.
4. Brown rape oil. 5. Cotton seed oil.
5. Cotton seed oil. 6. Pale cotton seed oil. 6. Raw linseed oil. 7. Cotton seed oil.
7. Palm nut oil. Fig. 2. Case IV.
8. Linseed oil.
8. Ground nut oil. 9. Almond oil.
9. Castor oil.
10. Pure lard oil.
II. Common tallow oil. 12. Tallow oil.
12. American tallow oil. 13. Foreign neatsfoot oil. 13. English neatsfoot oil. 14. Neatsfoot oil.
14. North American neatsFish Oils.
15. American sperm oil. 17. Seal oil.
16. Whale oil.
18. Lubricating mineral oil, 21. Cod oil. 22. Newfoundland cod oil. 23. Raw cod oil. 24. East India fish oil.
25. Heavy mineral oil. diminution will not, however, follow the usual law of
26. inverse squares, but a more complicated law.
All these samples of oil, together with the slips of To be continued.)
metallic copper left in contact with them, were examined on the gth of August, 1876, in the following manner :
First.–Each slip of copper was carefully examined
and its appearance noted. ON THE ACTION OF DIFFERENT FATTY Second.—The appearance of each oil was observed and OILS UPON METALLIC COPPER.*
Third.—Ten grains of each sample were measured off By WILLIAM THOMSON, F.R.S.E., F.C.S.
by a pipette and placed in a small test-glass, and 5 grs.
of a moderately strong solution of ferrocyanide of potasWith the view to study the a&ions of different fatty oils sium added, and the oil and solution thoroughly mixed by upon copper I made two series of experiments. In the stirring them together for some time and then leaving first, which was commenced on the ist O&ober, 1875, I them for about a day. This method I found to give the took twenty-six different samples and measured 150 grs.
most satisfactory result for testing the relative proportions of each into bottles; into each bottle was then placed a of copper which had been dissolved by the oils; the charac. piece of copper foil, i inch long by finch broad, so as to teristic brownish red precipitate of ferrocyanide of lie flat at the bottom of the oil. After a few days it was copper being thrown down admitted of very accurate observed that some of the samples had acted on the pieces comparison. of copper, some had thrown on to the metallic surface a Fourth.–Fifteen grains of each oil were taken by slight greenish incrustation, some had produced a dark
means of a pipette, and each placed in a small stoppered coloured incrustation, and the remainder produced no
test-tube ; 15 grs. of distilled water were then added and effect on the bright metallic surface of the copper.
each tube shaken violently. The tubes were then sus. No special examination of either the metallic copper or
pended in water and heated to about 200° F. and shaken the oils was made till they had remained in contact for violently two more times at intervals of one hour each, ten months at the ordinary temperatures of the atmo. and allowed to remain in contact with the hot water at sphere.
200° F. for six hours; the source of heat was then re
moved and the oils allowed to remain over the night to * Read before the British Association, Glasgow Meeting (Section B.). I allow the water to separate from the oils more completely.