prevent oxidation or other deterioration of the surface of the mercury. For instance, it was anticipated that nitrogen with traces of oxygen and water vapour might give rise to nitric acid and cause trouble. Hydrogen forms no compound with mercury, and was tried in the first instance. It proved completely successful. Last winter the regulator was kept working day and night for six months, maintaining a temperature of about 18° C. No tarnishing of the mercury surface has taken place, and it seems as bright as when it was first installed. A point of importance is that the regulation is independent of variations of atmospheric pressure, owing to the gas being completely enclosed and working against a absolute temperature. sectional area of tube at A in cm2. sectional area of tube at B. = distance of mercury surface at в, below platinumpoint in mm. filling is secured by the use of a small tube c, which is sealed with a blowpipe when the mercury and toluene are in place. It is not difficult to fuse the tube c when filled with toluene, as the heating causes the toluene to boil near c and fill the tube with vapour, which excludes air, so that when the tube cools it is filled with toluene right up to the end without an air-bubble. D is the gas inlet pipe, which is closed by the expansion of the mercury. E is the gas outlet pipe. The tube D is kept in place by a rubber stopper, which permits of its ready removal. Regulation to any desired temperature is easy. The regulator is placed in the bath, which is kept at the desired temperature for a few minutes. The tube D is removed, and an excess of mercury poured in. When the temperature is as desired, the excess of mercury is sucked out with a filterpump through the tube D. Thus the right quantity of mercury is obtained corresponding to the required temperature. This form of regulator is affected by variations of gas and atmospheric pressure. It is not difficult to secure regulation of the thermostat within o'or° C. h = mean height of mercury level at A, above platinum- VOLUMETRIC DETERMINATION OF MERCURY. i.e., point in mm. For greatest sensitiveness B A de dx 1)v + 1). must be as small as With these dimensions 1 mm. fall of the mercury contact surface at B corresponds to o'4° C., or o'or° C. to onefortieth of a mm. The sensitivneess realised depends of course upon the activity of stirring of the contents of the thermostat. The comparative sensitiveness relative to that of a regulator depending on this expansion of mercury or toluene is chiefly influenced by the fact of the small heat capacity of the hydrogen contained in the bulb and the large surface available for rapid heat exchange. Water-bath Regulators.-This is a modified form of Lowry gas regulator. It was designed in the form of a grid, so as to be placed near the side of a large water-bath, in order to take up as little room as possible. The last U-shaped limb, Fig. 2, contains mercury from B to A. The remainder, from A to c, is filled with toluene. Easy By CARL E. SMITH. ABSTRACTS of a report by a Committee of the Division of Pharmaceutical Chemistry of the American Chemical Society have appeared in recent journals (see American Journal of Pharmacy, 1911, lxxxiii., 186), the work reported on being a comparison of various methods for the determination of mercury in the medicinal compounds of this metal. The purpose of these notes is to relate some recent experiences with two of these methods, which are probably the simplest and most reliable of those mentioned in the report, the Hempel method for mercurous and the Rupp method for mercuric compounds. It is desired also to call attention to one other, which is perhaps the best volumetric method available for some purposes. The writer's experience with the Hempel method, in its application to calomel and mercurous iodide, corroborates to a considerable extent the results of the committee. The objectionable feature of it, noted by several of the members, that long-continued shaking is needed to bring the salt into solution, may be eliminated, it was found, by the simple change of adding the iodine solution first, instead of the potassium iodide. When this is done and the mixture at once shaken vigorously in a stoppered flask, solution is effected very quickly. The final result is the same in either case, as comparative trials have shown. It seems advisable, also, to increase the quantity of sample, to lessen the experimental error, in the case of calomel to about I grm. The most satisfactory results were obtained when working in the following manner :-To about I grm. of calomel, accurately weighed, contained in a glassstoppered 300 cc. Erlenmeyer flask, add 50 cc. of N/10 iodine solution. Mix by rotating until the salt is thoroughly moistened, then add a solution of 2 grms. of potassium iodide in 10 cc. of water, and at once shake the stoppered flask vigorously until solution is complete. Titrate the excess of iodine with N/10 sodium thiosulphate, using starch solution as indicator, adding the latter when the liquid is nearly decolorised. Each cc. of N/10 iodine solution consumed corresponds to o'02355 grm. of mercurous chloride. A sample of calomel, practically chemically pure, assayed by this method 99.5 to 100'0 per cent, the average of six determinations being 99.7 per cent, with some variation in the working details. Practically the same figures were obtained with yellow mercurous iodide containing slight traces of impurities. The criticism of the Rupp method, that reduction of the mercury is not complete within a reasonable time without the use of heat, and that, when heat is employed, the CHEMICAL NEWS, Chemical Nature of Soil Organic Matter. 15 small flask with 25 cc. of 12.5 per cent hydrochloric acid on a water-bath. Mix frequently by rotating the flask during ten minutes. Pour the acid liquid into a 100 cc. flask, rinse the vaseline and flask repeatedly with water, and dilute the combined liquid and washings to 100 CC. Transfer 25 cc. to a glass-stoppered flask, add 1 grm. of potassium iodide, and proceed further as directed for the assay of mercuric chloride tablets. Each cc. of N/10 iodine solution consumed corresponds to o'01257 grm., approximately, of ammoniated mercury. Heat Mercury Plaster.-Contains 20 per cent of mercury; made with lead plaster, wool fat, and yellow wax. about 3 grms. of the plaster mass, accurately weighed, with 20 cc. of nitric acid, sp. gr. 1.38 to 1·40, in a flask having a wide neck and connected with a reflux condenser. Heat about ten minutes, or until mercury globules are no longer visible in the sandy deposit of lead nitrate, add 25 cc. of water, and heat again until the fat has separated, leaving the aqueous layer clear. Cool and pour the solution through a tuft of absorbent cotton into a 100 cc. flask. Break up the disk of fat, rinse it and the flask with 4 or 5 portions of 5 cc. each of water, and to the combined liquids add potassium permanganate until permanently red or until brown flakes separate. Decolorise or clarify the solution by addition of ferrous sulphate solution and dilute to 100 cc. To 25 cc. of the solution add 2 cc. of a 10 per cent solution of ferric_alum, and titrate with N/10 ammonium sulphocyanate. Each cc. consumed corresponds to o'o100 grm. of mercury. mercury is not easily dissolved afterwards, is well founded, if Rupp's directions in outlining the method (Berichte, 1906, xxxix., 3702) be taken literally as regards the quantity of alkali to be used. While his directions lead to the inference that only enough is required to combine with the acids formed by the reaction, his figures in the same paper show that he used a decided excess, not less than 10 cc. of normal solution for o'2 grm. of mercuric chloride. The divergent opinions regarding this method by the members of the committee are doubtless due chiefly to differences in the quantities of alkali used. When the Mercuric Salicylate.-Contains about 55 per cent of above mentioned proportions are taken the reaction is mercury. Dissolve about 03 grm. of the salt, accurately almost instantaneous, unless the solution is excessively weighed, in dilute sodium hydrate solution, acidulate with diluted, and may safely be regarded as complete within acetic acid, and add 25 cc. of N/10 iodine solution. Let five minutes, without heating. It will do no harm to use the mixture stand in a closed flask for three hours at room a still larger excess of alkali or to let the mixture stand temperature, rotating it occasionally. Titrate the excess longer. Shaken in a stoppered flask with the iodine solu- of iodine with N/10 sodium thiosulphate solution. Each tion, the precipitate is then dissolved very readily. A cc. of N/10 iodine solution consumed corresponds to large excess of acetic acid is to be avoided, as it tends to 0'0100 grm. of mercury. make the result too low, which is also the experience of of Mr. L. D. Havenhill of the committee. The best results were obtained by carrying out the details as follows: Dissolve about o'5 grm. of powdered mercuric chloride, accurately weighed, contained in a glass stoppered 300 cc. Erlenmeyer flask, in a solution of 2 grms. of potassium iodide in 10 cc. of water. Add 25 cc. of normal caustic alkali solution and 6 cc. of 40 per cent formaldehyde solution. Mix by swirling the flask occasionally during ten minutes, then acidulate with about 5 cc. of 36 per cent acetic acid. Add 50 cc. of N/10 iodine solution and shake vigorously in the stoppered flask until the mercury is dissolved. Titrate the excess of iodine with N/10 sodium thiosulphate solution, adding starch solution when the liquid is nearly decolorised. Each cc. of N/10 iodine solution corresponds to o‘01355 grm. of mercuric chloride. Chemically pure mercuric chloride gave by this method 99.8 to 100.3 per cent, with an average of 1001 per cent in five determinations. Similar results were obtained with mercuric iodide, oxide, ammoniated mercury, and mixtures of mercuric chloride and ammonium chloride coloured with aniline dyes. It is the official method of the German Pharmacopoeia, 5th revision, 1910, for the assay of mercuric chloride tablets and ointment of ammoniated mercury. The third method alluded to above consists in the titration of mercuric compounds, in nitric acid solution, with sulphocyanate in exactly the same way as the titration of silver. It is not applicable in presence of chlorides, and probably not in presence of other halogens. It was first made serviceable for accurate work by R. Cohn (Ber., 1901, xxxiv., 3502) and simplified by Rupp and Kraus (Ibid., 1902, xxxv., 2015). For illustrations of its application see below. The writer has no personal experience with this method, but his associates have found it accurate and useful for the assay of technical mercuric oxide containing iron. The German Pharmacopoeia uses it for the assay of several galenical preparations. For the convenience of any readers of this journal interested in the subject who may not have access to this book, the assay methods for mercury preparations prescribed therein are given here :Mercuric Chloride Tablets.-Composed of equal parts of mercuric chloride and sodium chloride, coloured with aniline dye. Dissolve two tablets of about 1 grm. each, accurately weighed, in water and dilute to 100 cc. 20 cc. of the solution dissolve I grm. of potassium iodide, add 10 cc. of a 15 per cent solution of potassium hydrate and 3 cc. of a 40 per cent solution of formaldehyde with 10 cc. of water. After one minute add 25 cc. of 30 per cent acetic acid, 25 cc. of N/1o iodine solution, and shake until the mercury is dissolved. Titrate the excess of iodine with N/10 sodium thiosulphate solution, using starch solution as indicator. Each cc. of N/10 iodine solution consumed corresponds to o'01355 grm. of mercuric chloride. In Ointment of Ammoniated Mercury.-Consists of 10 per cent of ammoniated mercury and white vaseline. Heat about 5 grms. of the ointment, accurately weighed, in a Mercury Ointment.-Contains 30 per cent of mercury; made with wool fat, pea nut oil, lard, and mutton tallow. Proceed as directed for the assay of mercury plaster, using about 2 grms. of the ointment and 20 cc. of nitric acid. Ointment of Red Mercuric Oxide.-Contains 10 per cent of mercuric oxide; made with white vaseline. Proceed as directed for the assay of mercury plaster, using about 5 grms. of the ointment and 20 cc. of nitric acid. Continue heating until the red colour of the mercuric oxide has disappeared. Each cc. of N/10 ammonium sulphocyanate solution corresponds to o'0108 grm. of mercuric oxide. The factors given throughout these notes are based on the atomic weights having Ŏ= 16 as the standard. If the volumetric solutions used are made by the H= I standard, either the factors or the final results should be multiplied by o'992.—American Journal of Pharmacy. CHEMICAL NATURE OF SOIL ORGANIC By OSWALD SCHREINER and EDMUND C. SHOREY. PARAFFIN HYDROCARBONS. THE paraffin hydrocarbons represent the simplest form of organic compounds and are widely distributed in nature. The lowest member of this group, methane or marsh gas (CH4), is a constant product of the decomposition of organic matter under certain conditions. Higher members of the group, liquid and solid, occur as mixtures very widely distributed in the earth's crust as petroleum, * Bulletin No. 74, U.S. Department of Agriculture, Bureau of Soils. asphalt, or similar deposits and also in mineral resins. The occurrence of paraffin hydrocarbons in plants is not very common, and so far as observed is confined to a few members of the group and to a few species of plants. The large deposits in the earth's crust can not, then, be attributed to the accumulation of unchanged plant residues, and a great many theories have been propounded to account for these deposits, most of them based on some transformation of organic material. In spite of the fact that these hydrocarbons are of rather rare occurrence in plants and are seldom added to soil in plant débris, the wide distribution of extensive deposits of such compounds and the occurrence also of mineral resins and shales from which hydrocarbons can be obtained in the rocks from which soils are formed might lead one to expect to find some trace of these compounds in the soil. The question is also raised by this consideration whether some of the processes by which hydrocarbons have been formed from more complex organic compounds may not take place in the soil and escape recognition because the conditions are not favourable for the accumulation of these products in the soil. The production of the simplest paraffin hydrocarbon, methane, is known to take place in soil organic matter when submerged under water, as in swamps. The production here is supposed to be due to the activity of anaerobic micro-organisms, but it is not known that absolutely anaerobic conditions are essential to this production or that methane may not be formed in small quantities in ordinary soils. Methane is present in the gases from the combustion of fuel even when excess of oxygen is available, and it has been found in the combustion of organic compounds in elementary analysis that some of the carbon may be present in the products of combustion as methane instead of carbon dioxide, and this when the combustion was carried on in pure oxygen (Dunstan, Proc. Chem. Soc., 1896, xii., 48). It may be, therefore, that in the decomposition of organic matter the formation of methane rather than carbon dioxide depends on the structure or constitution of a portion of the material decomposed, and similarly more complex members of this series may also be formed. In connection with this discussion of hydrocarbons in soils it should be noted that there are in nearly all soils dark coloured particles of organic matter that are very resistant to solvents and the action of either acids or alkalis. These sometimes are evidently particles of charcoal or coal that may have found their way into the soil, but a considerable portion is often made up of structureless bituminous-like material having the elementary composition so far as examined of lignites or brown coals. Whether this is formed in the soil is a matter for further investigation. Since such material often makes up a considerable portion of the organic content, its composition, constitution, and origin should be considered. One paraffin hydrocarbon has been isolated from a soil, and while in this particular case there is nothing to indicate that it may not be an unchanged plant residue, the isolation is of interest not only in accounting for a small portion of the organic matter, but also in that it opens up the question of a possible connection between the processes that go on in the soil and the processes by which paraffin hydrocarbons have been formed in nature. Hentriacontane, C31H64. A peaty soil from North Carolina containing 27 per cent organic carbon when extracted with boiling 95 per cent alcohol yields a dark coloured extract, from which on cooling a light yellow micro-crystalline body separates. This material was separated by filtration and the alcohol removed from the filtrate by evaporation, the volume being kept constant by the addition of water. There was thus formed a reddish brown precipitate which after separation and washing was in the form of a brown resinous powder. Extraction of this with boiling petroleum ether yielded a light coloured solution, which after removal of the petroleum ether left a light yellow oily residue. This was saponified with alcoholic potash, the alcohol removed, and the soap dried and extracted with petroleum ether. On evaporation of the petroleum ether the residue was a light coloured waxy mass, completely soluble in a relatively large volume of hot alcohol. On cooling the alcoholic solution so ob. tained, there was a separation of a feathery micro-crystalline body which was collected, washed, and purified by re-crystallising several times from alcohol. As thus obtained, the body was a hard waxy mass, melting at 68° C., and having a specific gravity of 0.780 at its melting-point. It was readily soluble in ether and petroleum ether, difficultly soluble in hot and very slightly soluble in cold alcohol. It was unacted on by fuming nitric acid at room temperature and did not absorb bromine. Elementary analysis gave the following figures:: in the paraffin residue of some petroleums. It has also Hentriacontane is a member of the paraffin series found been found in beeswax, together with another member of the same series, heptocosane, C27H56 (Schwald, Ann. Chem., 1886, ccxxxv., 117). It occurs also in some plants, having been found in the leaves of Gymnema silvestre (Power and Tutin, Pharm. Journ., 1904, [4], xix., 234), in tobacco leaves (Thorpe and Holmes, Journ. Chem. Soc., 1901, lxxix., 982), and in East India Ko-sam seeds (Brucea sumatrana) (Power and Lees, Pharm. Journ., 1993, [4], xvii., 183). With this information regarding its occurrence as a natural product, and in the absence of any information regarding the possibility of its formation from other soil organic matter, this paraffin hydrocarbon may be regarded as an unchanged plant residue. HYDROXY-FATTY ACIDS. Hydroxy acids of the fatty series are very widely distributed in the vegetable kingdom. One or more of the three hydroxy acids-malic, citric, or tartaric-is usually present in an acid plant or fruit juice, and some of the less common, such as glycollic, also occur in plants. Some members of this group can be formed by micro-organisms from more complex material-lactic acid by the lactic fermentation of sugar and citric acid by citromycetes (Mazé, Ann. Inst. Pasteur, 1909, xxiii., 830). All members of the group, however, seem to be readily broken down by other bacteria or fungi into simpler compounds with the loss of the hydroxy character. Lactic acid goes readily to butyric and others to acetic or formic acid or formaldehyde. In view of this fact, while there is no doubt that vegetable acids of this group are added to soils in large quantities and become temporarily, at least, a part of the organic matter of the soil, it does not seem likely that they would persist unchanged for any length of time. Two hydroxy acids of the fatty series have been isolated from soils, but neither are known as natural products. These are a-hydroxystearic acid and the dihydroxystearic acid previously described (Bull. 53, Bureau of Soils, U.S. Dept. Agr., 1909; Journ. Am. Chem. Soc., 1908, xxx., 1599). Both must be looked on at present as the products of the action of micro-organisms, probably fungi, on some of the organic matter known to be of plant or animal origin. While at present little is known of the processes by which these compounds are formed in the soil, and little can be said that is not of a speculative nature, it may be of interest at this point to note the laboratory methods by } Chemical Nature of Soil Organic Matter. CHEMICAL NEWS Jan. 12, 1912 which hydroxy acids are formed. Three general methods are known by which the hydroxy acids are formed from the corresponding acid. These are:-Making a halogen substitution product and treating this with silver oxide and water; making an amido derivative and treating this with nitrous acid; and making a sulphonic-acid derivative and treating it with caustic potash. In attempting to find a parallel between these reactions and the processes likely to take place in the soil, the second method seems to be the only one that offers any foundation for a theory. It is known that amido compounds result from the decomposition of more complex nitrogenous compounds and may possibly be formed or built up by the action of ammonia which is commonly formed in soils. Nitrous acid, as the result of denitrification or as the first stage in the change of ammonia into nitrates, is formed in nearly all soils and would supply the reagent required in the second stage of the reaction." In addition to these purely chemical methods of formation, there are the biological formations by fungi or bacteria to be considered, but this would lead somewhat afield from the purposes of the present Bulletin. a-Monohydroxystearic Acid, C18H3603. When the humus extract of a soil obtained by extraction with dilute alkali is acidified, a brown or black flocculent precipitate of the so-called humus bodies is formed. If this precipitate is separated by filtration, washed, and treated while still moist with boiling 95 per cent alcohol, a portion of the precipitate goes into solution. The amount of the humus precipitate so dissolved varies with the character of the soil treated, but the alcoholic solution obtained in this way is always dark coloured. On careful evaporation of this alcoholic solution, adding water to keep the volume constant until the alcohol is removed, there is formed a brown or reddish brown precipitate, which can be separated by filtration. When so separated, washed, and dried it is in the form of resinous lumps or powder, varying in colour, melting-point, and composition with the soil from which it was obtained. 17 This composition corresponds with that of the monohydroxystearic acids, two of which are known, designated a and respectively, and having the formula C18H3603. The properties of the acid isolated from the soil fix it as the a-acid. The a-acid is much less soluble in alcohol than the 3-acid, and the s-acid, moreover, forms an anhydride on heating with hydrochloric acid, which is not the case with the a-acid nor the acid from the soil. The melting-points of the - and 3-acids are so nearly the same that this property can not be used to distinguish between them. The melting-point of the pure a-acid, artificially prepared, remained unchanged on mixing with the acid from the soil, and this fact, together with the composition found and sparing solubility in alcohol and failure to form an anhydride, is sufficient to establish the identity of the acid from the soil as a-monohydroxystearic acid. a-Hydroxystearic acid is easily made in the manner described by Sadomsky (Ber., 1891, xxiv., 2388). When stearic acid is treated with red phosphorus and bromine, a-bromostearic acid is formed. On heating this with alcoholic potash the potassium salt of a-hydroxystearic acid is formed, and on acidifying the aqueous solution of this salt the acid is set free and can be extracted with ether. a-Hydroxystearic acid is not known to occur in any natural animal or vegetable product, and up to the present has been isolated from only one soil. On extracting this resinous material with petroleum ether there is obtained an extract generally colourless or light coloured, which on evaporation of the petroleum ether leaves a residue which may vary from an oily semi-known as a natural product it must be remembered that solid mass to a waxy solid. This residue is generally wholly soluble in hot alcohol. From this alcoholic solution there sometimes separates on cooling a white or yellowish microcrystalline mass or powder which in the case of one soil has been identified as a-hydroxystearic acid. The possible origin of this acid has already been discussed from a speculative point of view, and while it is not The soil from which this compound was obtained was a sample of Elkton silt loam, a type covering a considerable area in Maryland. This soil is almost white in colour, high in clay and silt, and contains o'53 per cent organic carbon and o-066 per cent nitrogen. The sample examined was one of several hundred pounds obtained from the Eastern Shore of Maryland. This soil when treated with 2 per cent sodium hydroxide solution yields an extract much darker than might be expected from a soil so light in colour. From this brown alkaline extract there is precipitated on acidifying with sulphuric acid a brown flocculent mass. On separation of this by filtration, washing, and treating with boiling 95 per cent alcohol, there is obtained an alcoholic solution nearly as dark in colour as the original alkaline extract. The precipitate formed by evaporation of the alcohol and addition of water was, after filtration, washing, and drying, a brown mass easily pulverised. Extraction of this brown powder with petroleum ether and evaporation of the solvent left an oily semisolid light yellow mass, which was completely soluble in hot 95 per cent alcohol. On cooling this alcoholic solution there separates a yellow microcrystalline powder, which after separation by filtration, washing with cold alcohol, dissolving again in hot alcohol, and repeating the separation several times, can be obtained free of colour and of constant melting-point. natural fats and oils are usually complex mixtures of glycerides, and that the chemistry of such glycerides as occur in these products in small amounts is very incomplete. More complete chemical knowledge of the natural fats and oils may show the presence of a monohydroxystearic acid. The method of its laboratory preparation does not suggest any possible parallelism in the soil as was the case when the origin of dihydroxystearic acid was under discussion. In the earlier literature of the hydroxystearic acids there is some confusion of nomenclature, as well as disagreement regarding their constitution. The 3-acid described by Saytzeff (Fourn. Prakt. Chem., 1887, [2], xxxv., 369) was designated as the a-acid by Geitel (Fourn. Prakt. Chem,, 1888, [2], xxxvii., 53). The designations a- and 8-acid seem to have been used primarily to distinguish isomers, the constitution of which were not known. The constitution, as now accepted and established by Shukoff and Schestakoff (Journ. Prakt. Chem., 1903, [2], lxvii., 415), is not in harmony with the common meaning of a and 3 designations. In the simple hydroxy-fatty acids the term a is applied to that acid having the hydroxyl group next the carboxyl group, for example, a-hydroxypropionic acid (lactic) is represented thus : CH3.CHOH.COOH; the term 8 is applied to that acid having the hydroxyl on the second carbon atom, for example, 8-hydroxypropionic (hydracrylic) is represented thus: CH2OH.CH2COOH. The constitution of the aand 3-hydroxystearic acids is represented as follows: a - acid, CH3(CH2)6 CHOH(CH2), COOH; B - acid, CH3(CH2)7CHOH(CH2)8COOH. In neither case is there a- or 3-structure. The authors in discussing these formulæ used the designations: 1. II. for the a-acid and 1. 10. IF 16 grms. of oxygen gas at o° C. are placed in contact with 2016 grms. of hydrogen gas at the same temperature, and both under atmospheric pressure, no reaction is evident. But if a negligible amount of heat be supplied to the mixture in the form of an electric spark, a violent reaction takes place, and 18.016 grms. of water are formed, and 68,511 calories of heat are given out (Mixter, Am. Journ. Sci., 1903, [4], xvi., 214). (The value given is the mean of the values obtained by Thomsen, Schuller and Wartha, Than, and Mixter, after reduction to the calorie at 15° to 16° as the unit; Mixter thinks the value correct to onetenth of 1 per cent). If the reaction took place at a different temperature, or under different conditions of pressure or volume, the amount of heat evolved would have been different, but the chemical reaction in each case would have been the same. From whence came the enormous amount of heat given out by the reaction? Why and how does the amount of heat given out vary under different conditions? Why did not the reaction take place when the hydrogen and oxygen were first mixed? It is the purpose of this paper to answer these questions and to point out certain facts concerning chemical energy, and certain possibilities regarding the relation of chemical energy to electrical and other forms of energy. The Source of the Energy given out by the Reaction. If the term "absolute zero of temperature" be used, some one will object that there may be no absolute zero of temperature, that we are not certain of the existence of molecules, and that if they do exist we certainly do not know that they cease to move at the so-called absolute zero. Granting for the present the validity of the objection, we will not use the term absolute zero, but will speak of - 273° C. No one will deny the existence of that temperature since a temperature below - 260° C. has already (c) Dewar, Proc. Roy. Soc., A, 1905, lxxvi., 325; 1902, lxix., 361; 1904, lxxiii., 251. He determined the specific heat of ice, -252.6 to - 188 = 0.146, -78 to - 188 0 285, 78 to -18° = 0'403. (d) Wiedemann, Pogg. Ann., 1876, clvii., 1; Phil. Mag., 1876, [5], ii., 81. = (e) Alt, Zeit. Phys. Chem., 1905, li., 252; Phys. Zeit., 1905, vi., 346; Ann. der Physik., 1904, xiii., IOIO; "Dissertation," Munchen, 1903. (f) Regnault, Mem. de l'Acad., 1862, xxvi., I. (g) Smith, Phys. Rev., 1903, xvii., 193. The total heat necesssary to raise these substances from -273° to o° C. may therefore be estimated as follows: The 18-016 grms of water at o° C. contain, therefore, at least 2887 calories, and since 68,511 calories of heat were given out by the reaction of the hydrogen and oxygen gases, these gases before the reaction contained at least 71,398 calories of energy. Of this total amount of energy, 2125 calories were supplied to the 2016 gims. of hydrogen, and 1972 calories were supplied to the 16 grms. of oxygen, in converting them from the solid condition at -273° C. to the gaseous condition at o° C.—a total of 4097 calories. It follows therefore that while in the solid condition at - 273° C. the oxygen and hydrogen contained at least 71,398-4097 = 67,301 calories of energy. Now, Dewar (Proc. Roy. Soc., 1904, lxxiii., 251) has shown by slight extrapolation of measurements extending to -258.9° C. that the molecular volume of oxygen at -273° C. is 21.21 cc., of hydrogen 24.18 cc., and of ice 19.21 cc. Therefore the 16 grms. of oxygen and the 2016 grms. of hydrogen together at -273° C. occupy 34'78 cc., and when occupying this volume at that temperature they contain 67,300 calories more of energy than does the 18-016 gims. of ice which they form if united, and which occupies a volume of 19:21 cc. There is no supposition whatever connected with this fact, except the slight uncertainty due to the measurements and their extrapolation, and this uncertainty is probably not greater than 100 calories. A study of substances |