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257 ON NITROGEN IODIDE,
a large excess of the strongest liquid ammonia kept at or
below 0° C. by a freezing mixture, the liquid poured off from By J. W. MALLET.
the easily subsiding black powder, and replaced two or
three times by fresh solution of ammonia. The powder The various researches upon the highly explosive black was then at once transferred to a corked flask, and shaken substance formed by the action of iodine upon ammonia up repeatedly, first with alcohol of 95 per cent., then with have, as is well known, led to different views of its com- absolute alcohol, and finally with anhydrous ether, all of position. That first put forward by Colin and Gay. these liquids being artificially cooled. Most of the last Lussac, nanely that it is nitrogen tri-iodide, appeared to portion of ether, which, as well as several of the preceding have been set aside by the experiments of Serullas,* washings, was perfe&ly colourless, having been devanted Millon,t Bineau, Gladstone, Playfair, and Bunsen,ll off, the Auid black mud was turned out upon a fiier, all of whom found hydrogen to be a constituent, but in drained in a few moments, and the remains of the ether varying amount, the formulæ NHI2-NH2I-NH3.N13–swept away as vapour by placing the filter and contents and NH3:4N13 having been assigned to the products under a receiver and drawing cold dry air through in a obtained by somewhat different processes, until more rapid stream.
This use of alcohol and ether to rerecently Stahlschmidt has revived the statement that move water from the iodide after its formation is not under certain conditions at least the simple tri-iodide is
to be confounded with the employment by several exformed.
perimenters of alcoholic solutions of iodine or ammonia, One source of error in the analysis of this instable com- or both, in making the substance in the first instance. pound seems to have received insufficient attention from The product thus obtained was explosive in the some of those who have examined it, and somewhat highest degree, yielding to very slight friation upon paper, affects the conclusions drawn from the experiments of frequently producing a crackling sound from little partial others. The substance, obtained as a black powder by explosions when it was gently rubbed under water, and the action of iodine on ammonia, decomposes gradually in two instances exploding in some quantity under water, in contact with water, nitrogen gas being slowly evolved, with much violence and complete shattering of the iodine liberated, and iodic and hydriodic acids or ammo.
vessel. nium salts formed. This decomposition takes place to no
The relative quantities of nitrogen and iodine were inconsiderable extent during the drying of the powder at ascertained by decomposing an unweighed parcel of the ordinary temperature, and may be readily proved to have substance by a moderately strong aqueous solution of occurred by treating the dry residue with any of the sol. sodium sulphite, neutralised by dilute sodium hydrate, vents for iodine, as for instance alcohol, chloroforn, or and determining, in equal volumes of the liquid, the nicarbon di-sulphide, which at once form deeply coloured trogen as ammonia (expelled by boiling with excess of solutions. Hence the air-dried powder is really a mix. soda, and collected in sulphuric acid of standard strength), ture of the original substance or substances with various and the iodine as silver iodide. decomposition products, and so is unsuited for accurate A-In three experiments were obtainedanalysis. On the other hand, it might be doubted in
No. 2. regard to the analyses made of freshly prepared and still
O'126 0*184 moist iodide, whether the results apply to a substance
0:172 grms. Equiv. to N
O'104 capable of being obtained in the dry state without de
7607 6.889 Millon and Bineau, it is true, seem to have aimed at
Equiv. to I 2.771
3723 guarding against this difficulty by drying the materials, Nos. 1 and 2 refer to the same lot of material (separately side by side with solid potash, under a jar of gaseous decomposed, however) ; No. 3 to the product from a ammonia. Bineau remarks that some of the gas is at repetition of the same process. first absorbed by the water moistening the powder, but These numbers correspond tothat as the drying proceeds the gas recovers (“ à peu
3. Calc, for NIE. près ") its original volume, and that so moisture is gotten N (assumed) 14'0 14'0 14'0 14'0 rid of without the iodide being decomposed. But, with
373'02 378.74 367'04 38100 out qualitative examination of the gas, or a very accurate determination of its volume, this does not afford satis
or, for I atom of nitrogenfa&ory proof that the dry substance is unchanged. I
No. 2. have observed continuous, though slow, evolution of little Atoms of iodine
2.98 2.89 bubbles of nitrogen from the freshly prepared powder when kept under strong aqueous ammonia, though in this case
B—Another specimen, similarly prepared, but with no free iodine can be found, since as fast as it is liberated
weaker ammonia, without any precaution as to cooling the it reacts with the excess of ammonia, reproducing the materials used, and in a room the temperature of which nitrogen iodide, and forming more ammonium iodide,
was about 23° C., gavewhich latter therefore tends to accumulate in the liquid, and is thus to be found in the residue from drying up a moist NH3
grms. mass of the powder in an atmosphere of ammonia.
Equiv. to N
0'143 Oʻ125 I have applied a different method, which is often useful Ag 1
5'935 5'467 under other circumstances, for quickly getting rid of
Equiv. to 1
2'955 water, namely repeated and rapid washing with absolute alcohol, followed by ether, and final evaporation of the last.
corresponding tonamed volatile liquid.
N assumed) 14'00 14'00 20 or 30 grms. of iodine was dissolved in a minimum of
314'07 330°96 95 per cent. alcohol, and precipitated by pouring into a or, for one atom of nitrogenlarge volume of cold water. The finely divided iodine
Atoms of iodine
2'47 2.61 was washed several times by decantation, then gently triturated for several minutes in a porcelain mortar with C-Two other specimens, washed at first, not with alco.
hol and ether, but simply with water until no free am. * Ann. Ch. Phys. [2), 42 ; 200 (1829).
monia could be detected in the washings, then kept under + Ann. Ch. Phys. (2), 69 ; 78 (1833).
water for two or three days at ordinary temperature, i Ann. Ch. Phys. , 70; 270 (1838); and (3), 15; 71 (1945). Š Chem. Soc. . journ., 4; 34 (1851).
with occasional stirring, and finally dried after washing | Ann. Ch. Pharm., 84; 1 (1852).
out with absolute alcohol and ether, as above described, Pogę. Ann., 119; 421 (1863).
N 4°22 H 0'15
June 13, 1879. No. 1.
Experiments of Bunsen (first product, using anhydrous 0:136 Oʻ127 grms.
alcoholic solutions of ammonia and iodine). He Equiv. to N
himself assigned the formula NH3.NI3.
I-N=N-H, or 1-N=N-H. corresponding to
· I N (assumed).. 14:00 14'00
It is much more doubtful whether we should add-
267'12 264'27 or, for I atom of nitrogen
Experiments of Milon (in 1838). The product dried under
a receiver filled with gaseous ammonia had lost its Atoms of iodine
extreme explosiveness, and no doubt contained am. Of the above results
monium iodide. A distinctly represents the atomic ratio N:I=1: 3,
H fully confirming Stahlschmidt's conclusion that the
1-N=N-H, or H-N=N-H. tri-iodide can be obtained quite free from hydrogen.
H I B corresponds well with N:1=2: 5, and Ĉ with the proportion found as the result of several | It appears that, not only may these different products be earlier experiments, N:1=1:2.
obtained by varying the conditions under which the forIf В be admitted to stand for a definite compound, and mation of the explosive substance is effected, but during not a mere mixture of A and C, which is rendered pro: its decomposition by water, certainly involving more than bable by the fairly close agreement of the results obtained
a single series of reactions, one of these products may be with the calculated figures, there must be two atoms of nitrogen in the molecule, and the formula will be N2H15: Fournal.
more or less converted into others.-American Chemical This formula may almost as well be deduced from Bunsen's
University of Virginia, Feb. 21, 1879. anaylsis of one of the products he obtained (by addition of ammonia to a solution of iodine in nitro-hydrochloric acid, diluted with water, and rapidly washing with cold water) as that which he has himself assigned, viz., NH3.4N13, since the figures standCalc. for N,H1y. Calc. for NH3.4NI,. Found by Bunsen.
SOFTENING OF MAGNESIA-HARD WATER. 0.008143 or assumed 4:38
By J. GROSSMANN, Ph.D. 0:19 I 95.63 95.43 0'174417
9382* I have lately had an opportunity of making some experi.
ments on the softening of so-called magnesia-hard water
by Clark's process. Although from a theoretical point of It will be seen that the figures of the formula now pro- sosted as easily as ordinary (lime.)hard water, it was
view there is no reason why such water should not be posed differ less from those of Bunsen's scrmula than the thought convenient to try the experiment on a somewhat latter do from the results of experiment. In view of the general fact that the compounds of ni- large scale, especially as I have not been able to find
that any experiments on the softening of magnesia-hard trogen in which this element behaves as a pentad are
water have been published before in detail. those in which instability is chiefly observable, and
The water in question is pumped from a colliery at noticing the various proportions in which the iodine and Collins Green, near St. Helens. The bottom of the well hydrogen have been found together united with it, it seems
is about 964 yards from the ground, and I give for comfairly probable that the molecule of each of these explo, pleteness sake the different strata, as well as the quantity sive compounds contains two pentad nitrogen atoms ; and of lime and magnesia per hundred, which hydrochloric reviewing all that has been published on the subject, with
acid dissolved out of them, the samples being previously attention to the sources of error connected with the dried at 240° F. various methods used, we seem to have established the following series of substituted products, beginning with
P.c. CaO. P.c. Mgo. Yards. the tri-iodide :
Depth of alluvium and clay from
17 Experiments of Stahlschmidt (using aqueous ammonia)
red sandstone .. and those now reported (A).
New red sandstone
0:16 0'24 34 I Yellow sandstone
13 I_N= N-I.
Compact red sandstone
4972 0'37 I
New marl or metal
6 Dun Rock ..
0-40 0:46 Experiments of Bunsen (second product), and above Coarse porous red sandstone 1.88 0'27 13 result (B).
Coarse red sand ..
This water is organically very pure and contains only Experiments of Bineau, Stahlschmidt, Gladstone (using small quantities of chlorides and sulphates. The hard
alcoholic solutions of ammonia and iodine), and above ness is almost entirely temporary, though in estimating result (C).
the permanent hardness it is sometimes difficult to remove I -H НА
the lime and magnesia by boiling. I may as well point 1-N=N-H, or, I-N=N-I .
out in this place a common fallacy, which is that hard
water by being boiled before being used for domestic pur
poses becomes soft. As it is generally only healed to There seems to be an error in the calculation of the percentage of boiling just before being used for washing or cooking it iodine in the original paper (Ann. d. Ch. u. Pharm. ; 84; 1), but the figures here given are correctly deduced, I believe, from the actual
makes not much difference in the hardness of the water. weighings quoted, viz., 0-1300 grm. of ammonio chloride of platinum The following is taken from the Sixth Report of the Com. and 0'0732 grm. of palladium.
missioners appointed in 1868 to inquire into the best
, Nezys} Analysis of the Water of St. Dunstan's Well, Melrose. June 131879.
259 means of preventing the pollution of rivers. Thirteen water softens as well and as easily by Clark's process as samples of water drawn on thirteen different days from ordinary (lime-)hard water. the kitchen boiler of a dwelling-house, and from that of I wish to point out here that in my opinion, with our the Athenæum Club, were found to be usually nearly as present knowledge of the behaviour of magnesia-hard hard as the cold water with which those boilers were water towards soap solution, the hardness test in cases of supplied, as is seen from the following results :
water of that description cannot be relied on in any way.
Mr. Wanklyn, in his book “On Water Analysis," says
that magnesia takes up as much soap as it equivalents 14:6 136
of lime would take up. If that were so the Collins Green
water should have tested 35'9° total hardness, instead of
23.3°, which it gave on the most careful testing. It will
be noticed that this is even less than the water would
require if it contained an equivalent of lime for the
magnesia present ; for the calculated hardness would then 14'4
be 29:4°. It appears to me that in the case of magnesia
hard water a determination of the lime and magnesia is I boiled Collins Green water that tested 27.8° total the only means of showing the quality of the water. On hardness in an ordinary tea-kettle for five minutes, and the other hand, I quite agree with Mr. Wanklyn in putting even that exceptionally temporary-hard water tested then little reliance on the distinction between temporary and still 17.6° total hardness. The experiments for softening permanent hardness, unless the estimations have been this water by Clark's process were made in two series; performed very carefully ; and there are
cases in in the first milk of lime was used, and in the second lime- which, even with the most careful working, figures for water. The milk of lime was prepared by mixing 5 lbs. temporary and permanent hardness may be got which are of slaked lime of 70 per cent CaO with 6 gallons of Collins not trustworthy. Green water. In performing the softening of the water the milk of lime was gradually added to the water during the operation, the mixture being well agitated during the whole experiment.
ANALYSIS OF THE In three experiments the hardness was reduced from WATER OF ST. DUNSTAN'S WELL, MELROSE. 23:3° which the water tested originally to 5'0°, 5'5°, and
By WILLIAM JOHNSTONE, F.C.S., F.I.C. 5*7o. The total solids were reduced respectively from 339 to 13'0, 33.6 to 12-2, and 33:6 to 136 grs. per gallon. The softened water, after it had been standing in stoppered An exhaustive analysis of this strongly ferruginous saline bottles for a few days, formed a little deposit, and its carbonated water has not, so far as I have been able to hardness was then 3'5° in all cases. The analysis | learn, been published before, although a general analysis showed that then the lime had been reduced from 9:13 to of it was made by Mr. J. Dewar in 1870, and published 1:62 ; the magnesia from 5'23 to 0'23 grs. per gallon. in the Chemical News, vol. xxiv., p. 171. There has
There were used on an average 1465 gallons of water been a partial analysis of this water also by Dr. Stevenson to 3'5 lbs. of Cao, corresponding to 2.67 lbs. of lime of Macadam, of Edinburgh, but as his results are very 90 per cent per 1000 gallons. Theoretically to precipitate doubtful I refrain from quoting it at all. As this water the lime and magnesia as far as I have done in my is peculiar for the large quantity of iron it contains, and experiments would require 2'31 lbs. of Cao per 1000 as its composition seems to have varied considerably gallons.
since it was examined by Prof. Dewar, it is thought that The experiments for softening with lime-water were another and more complete analysis will not be out of carried out in a similar way. A measured quantity of the place. lime-water was put into the mixing tank, and the Collins Melrose is a village of some 2000 inhabitants, and is Green water run into it until nearly all the lime of the situated at the base of the Eildon Hills, in the valley of former was taken up, which in these experiments as well the Tweed; one of those lovely spots that are said to be as in those with milk of lime was ascertained by the well particularly favourable to the curative effects of medicinal known silver test. The mixture was well agitated during waters. The surrounding country consists principally of the whole experiment. A great advantage in working richly variegated fields, and the entire distrid teems with with lime-water is that it requires less agitating than objects of natural beauty, while every spot on which the working with milk of lime.
eye rests is associated with some incident of historic or In four experiments the hardness was reduced from classic interest—the ecclesiasticism and chivalry of the 23:3°, which the water tested originally, to 3.5°, 3:3°, 3.5°, past, and the interest conferred by Scott in the present. and 35°.
The total solids were reduced respectively The salubrity of the district is well known, and the from 34'3 to 12'0, 3484 to 11'2, 34:6 to 12'0, and 347 to romantic scenery, which is equalled by few places in the 11•2. The lime had been reduced from g'07 to 1.67, and kingdom, presents a picture dear to the lover of nature as the magnesia from 5'24 to o'18 grs. per gallon.
well as to the invalid. There were used on an average 1670 gallons of water The spring, which belongs to Mr. John Turnbull, of on 530 gallons of lime-water, which latter having been St. Dunstan's Cottage, Melrose, was accidentally disexposed to the air for some time before being used tested covered in 1870, when sinking a shaft for ordinary spring only 60 grs. CaO per gallon. This corresponds to one water. The water is said to be uniform in quantity, its volume of lime-water of 60 grs. Cao per gallon to temperature varies only within very narrow limits, and is 3.15
volumes of Collins Green water, or corrected to go grs. quite cold. As it occurs in the spring it is perfe&ly clear, of CaO per gallon, which strong lime-water should con- of a yellowish colour, but, after exposure to the air, tain, the proportion of lime-water to Collins Green water deposits the iron as a ferric mangano-manganic oxide; would be i to 4872. This result is not quite correct, as it has a strong powdery odour and a decided inky taste. the lime-water had undergone a further susceptible de. When taken from the well there is a disengagement ofsmall composition while lying in the mixing-tank; so that at the pearly bubbles, and on being shaken up in a closed bottle time of its adion on the Collins Green water it contained | liberates a large quantity of gas. The temperature of the less than 60 grs. CaO per gallon. Both in working with spring on October 5, 1878, was 50° F., the temperature of milk of lime and lime-water the softened water settled the air at the same time being 62° F. The specific perfe&ly clear after three to five hours, taken from the gravity of the water is 1001'9356. A careful qualitative time that the agitation was suspended.
analysis indicated the presence of the following con. From these experiments it follows that magnesia-hard stituents in estimable quantities :
Chemical News, 260 Contribution to the Theory of Fractional Distillation.
June 13, 1879.
0'009900 Lithium chloride
0'027528 Manganous oxide
Oʻ012511 In addition to the above were found traces of fluorine, Calcium carbonate
0'028544 butyric and phosphoric acids, along with other volatile Magnesium carbonate
0'037205 and non-volatile organic matter.
0:529553 The residue of 30 gallons was examined by means of Manganous carbonate
0.001278 the spectroscope for cæsium, rubidium, and thallium, but Silicic acid
0'027866 the search proved unsuccessful. The method of quanti- Crenic acid
0'013572 tative analysis employed was essentially that described by Apocrenic acid
0.000487 Fresenius under the head of " Analysis of Mineral Waters" in the last edition of his “Manual of Quantitative Total ingredients calculated
The following figures represent grammes per litre, and but at the same time I may mention that a considerable are the average of three determinations of each of the sum of money has been expended in the view of preventing principal constituents, done in order to guard against any more surface-water entering the well, so hope at some error and to ensure accuracy; the amount of water taken future date to be able to favour you with another analysis, for the several determinations was, whenever practicable, ascertained by weight.
Results of Analysis. Chlorine ..
PROCEEDINGS OF SOCIETIES.
0'000788 Sulphuric acid (SO3)
CHEMICAL SOCIETY. Carbonic dioxide (total)
Thursday, June 5, 1879. Silicic acid
0.035286 Ferrous oxide..
Mr. Warren De La Rue, President, in the Chair. Lime and strontia expressed as car. bonates
O'103842 After the transaction of the usual business the following Magnesia (total)
0'056216 certificates were read for the first time :-E. Buckney, Lime precipitated as carbonate on
R. E. Holloway, T. Blackburn, E. F. Mondy, E. Francis. boiling..
0'028544 It was announced that a ballot for the election of Fellows Baryta
0'002917 would take place at the next meeting of the Society Strontia
O'000886 (June 19). Manganous oxide.
0'000785 The following papers were read :Phosphoric acid
“ A Contribution to the Theory of Fractional Distilla. Alurnina ..
tion," by T. E. THORPE. Wanklyn some years ago found Lichia
that when two liquids of different boiling-points were mixed Potash
together in equal quantities by weight and distilled, the O'343063
proportion of each constituent in the distillate was the Ammonia
product of its vapour-density and vapaur-tension at the Total fixed constituents
temperature of ebullition of the fraction. Hence, under I'390000
certain circumstances the less volatile of the two subFollowing the arrangement adopted by Fresenius on the stances may pass over most rapidly, whilst if the vapourassumption that the strongest acids are united with the tensions and vapour-densities of the two liquids are instrongest bases, &c., and allowing for the fact that the versely proportional the mixture will distil unchanged. more or less degree of the solubility of the salts decidedly Berthelot observed that a mixture of 90'9 parts of carbon influence the manifestation of the affinities, and in order disulphide with gʻI parts of ethyl alcohol boiled and disto simplify reference and comparison, and by way of con
tilled as a homogeneous liquid. An instance of this phe. trast, i append the results calculated as grammes per equal volumes of carbon tetrachloride boiling at 76-6°, and
nomenon has been noticed by the author. A mixture of litre. (See next column.)
of methyl alcohol boiling at 65•2°, was distilled. It was Gases dissolved in the water and expelled by ebullition found that 46.5 per cent of the whole boiled constantly in vacuo measured at 59° F. and 760 m.m. barometer.
between 55-6° and 55'9", 10° lower than the boiling point Cubic centims.
of the most volatile constituent. This mixture contained Carbonic dioxide
78.1 per cent carbon tetrachloride and 219 per cent methy!
alcohol. This proportion, 3.6 to 1, is almost identical Nitrogen
with that obtained by multiplying the vapour-tensions of 31.250
the two liquids at the temperature of the boiling point of
the mixture (5507) by their respe&ive vapour densities, 139477
487-4X 15'97: 372.4 x 76.69::1:367. The distillation of I am unable at present to form an opinion as to whether the residue in the Hask was continued by Mr. C. C. Star. the composition of the water is constant, owing to the ling: at first principally carbon tetrachloride, finally pure surface water having had free admittance to the well pre- methyl alcohol passed over. The author suggests as a vious to the collection of this sample on March 18, 1879, striking lecture experiment the following :- Three baro
Chemical Dynamics. June 13, 1879.
261 meter tubes are filled with mercury. Into one some racter is that of a sigmoid. For a certain time there is methyl alcohol is passed ; into the second some carbon no perceptible action; this time is the longer the lower tetrachloride; into the third a mixture containing by the temperature. Reduction then commences languidly, volume 3 parts of methyl alcohol to 5 of carbon tetra- quickly accelerating until a maximum of activity is reached, chloride: the depressions of the mercury column are 80, after which it diminishes until almost perfect deoxidation 70, and 130 m.m. respectively. The author promises a is effected. The maximum rate of action with hydrogen further research on the physical peculiarities of this lies about 10 per cent (out of 19674 per cent) of oxygen orimixture.
ginally contained in the copper oxide, and about 7 to 8 “ Preliminary Note on the Action of Organo-zinc Com
per cent in the case of carbonic oxide. This apparently pounds on Quinons,” by F. R. JAPP. When finely-powdered | indicates that hydrogen passes through the outer and parphenanthren quinon is gradually added to zinc ethyl, diluted 'tially reduced surface of particles to their interior more with ether so as not to be spontaneously inflammable, a
readily than carbonic oxide. The following numbers reaction takes place with evolution of gas. The orange illustrate the maximum rates of reduction attained, the colour of the quinon disappears: a whitish powder is
gaseous currents being competent to remove o‘7791 per cent formed, which sinks to the bottom of the liquid. On de- of oxygen (out of 19*74) per minute :composing this product with an excess of alcohol, boiling,
Maximum rate Maximum rate and filtering hot, transparent, faintly yellowish, rectangular
Temperature. plates were obtained, fusing at 77o, and having the formula
Per cent per minute. Per cent per minute. C18H2003. This formula can be resolved into
0:480 The compound C16H1402 has not yet been obtained pure ;
O'118 but the monacetyl derivative, C16H1302(C2H30), has been
Oʻ570 prepared and analysed; it fuses at 103°. The author
0'270 refrains at present from discussing the constitution of the
0270 compound C16H1402, but suggests that these reactions
0*700 may serve to distinguish quinons from double ketons. He intends, also, to study the action of organo-zinc com
The higher the temperature the nearer does each curve pounds on other quinons and allied substances as di- approximate towards a limiting straight line, which would benzoyl.
be attained did deoxidation commence immediately and go After some remarks by Dr. ARMSTRONG on the interest on at such a rate that all the hydrogen was converted into and probable bearing of the above reaction,
water, and the carbonic oxide into carbonic acid. The Dr. WRIGHT read a paper entitled “ Third Report to the highest rates of reduction attained corresponded to a conChemical Society on Researches un some points in Chemical version of about nine-tenths of the H into H20, &c., of Dynamics (On the Curved Surfaces expressing the Rela- co into CO2. From the curves it is evident that, cæteris tions between Time, Temperature, and Amount of De: paribus, to perform a given amount of deoxidation with oxidation of Copper Oxide by Hydrogen and Carbon time than with carbonic oxide. The existence of a period
hydrogen requires either a higher temperature or a longer Oxide),” by C. R. A. Wright, A. P. LUFF, and E. H. Rennie. This is a continuation of the previous reports by the acceleration in the rate of action to a maximum, &c.,
of incubation " during which no action takes place, and the authors on the subject. In the present paper a large shows that what has been termeil “ Chemical Induction" number of observations have been made by reducing a uniform weight (1'15 grms.) of copper oxide (prepared by by Bunsen and Roscoe takes place in these cases to a large igniting pure copper, nitrate) in narrow glass U-tubes experiments now in progress this does not appear to be the
extent, dependent in amount on the temperature. From heated to known and constant temperatures in vapourbaths : in some cases water and paraffin baths were em.
case when copper is oxidised by hot air. A number of
observations were made on the effect of varying the speed ployed fitted with Page's gas-regulator. Equable streams of hydrogen and carbonic oxide were obtained by bubbling oxide used, with the general result that a more rapid
of the current of reducing gas and the weight of copper the gas through a wash-bottle, the stream being adjusted by a screw.clamp, and counting the bubbles. The average
stream or a smaller weight of copper oxide corresponds to rate was 12o5.c.c. per minute. By plotting
out the results Heating the copper oxide just before use causes great
an increased percentage of deoxidation, and vice versa. thus obtained in space with reference to three planes mutually at right angles, so that the distance from each irregularities in the action. A large number of observa
tions were made by enclosing the copper oxide in sealed plane represents, respectively, the time of exposure, the temperature, and the percentage loss of oxygen. Points tubes filled with the respective gases, heating for different are marked on curved surfaces, the sections of which, periods, and determining whether reduction had taken parallel to the three primary planes, represent respectively, The times are perceptibly longer than those found in the
place or not; thus the following numbers were obtained. the amounts of oxidation produced in giver times at a constant temperature, the times required to produce given corresponding U-tube experiments; in every case the time amounts of deoxidation at constant temperatures, and the at any given temperature is less with CO than with H. amounts of deoxidation produced at given temperatures in
With CO, period With H, period
Temperature. a constant period of time. The paper was illustrated by
of Incubation equals about
equals abouttables, diagrams, and models of the curves thus produced,
160° 12 minutes 80 minutes the mode of experimentation adopted being to determine
6 hours for a constant temperature the amounts of deoxidation
118 produced in varying times. At and above 160° in the case
28 of hydrogen, and 130° in the case of carbonic oxide, the curious result was arrived at that the same mean curve is
83.84 obtained whether the exposure be made all at once to a Attempts were made to trace out curves illustrating the temperature for a time, T, or in periods of time tı, ta, tz, rate of reduction at various temperatures in atmospheres &c., which are together equal to T, provided that the in- containing more reducing gas than would suffice to deterval between the periods is not too long (ten minutes). oxidise completely the Cuo. The results were not very Below the above temperatures the deoxidation in an hour concordant, but indicated that the action here is still of the is greater than that produced in two consecutive heatings same kind ; i.e., a period of incubation exists, after which of half an hour each with an interval between. The action commences, reaches a maximum, and then falls off ; curves obtained with hydrogen and carbonic oxide re- in other words, chemical induction takes place whether the semble cach other in certain respects; their general cha. I metallic oxide or the reducing gas be at any given moment