which may seem, from the analysis, to be worthy of more extended investigation. The amount of moisture is estimated by ascertaining the loss of weight on drying a small portion of the sample. The crude ash left after ignition is separable into the constituents that are soluble in water; those that are insoluble in water, but are soluble in dilute hydrochloric acid; and those which, insoluble in those substances, are soluble in sodic hydrate. The residue still undissolved consists usually of a little unconsumed carbon. The amount of nitrogen is determined by combustion with excess of soda-lime. Exposure of a part of the sample to the action of pure coal-tar benzole gives the benzole extract, which may consist of volatile oil removable by evaporation; alkaloids, glucosides, and organic acids, soluble in water; alkaloids, and possibly glucosides, soluble in dilute acids; chlorophyl and resins, soluble in 80 per cent alcohol; and wax, fats, and fixed oils which do not yield to either of the solvents. The part of the plant not dissolved by benzole is further treated with absolute alcohol, and afterward with other agents, as water, subacetate of lead, and dilute hydrochloric acid, as special tests. The part which remains insoluble, after treatment in alcohol, is exposed to the action of water; that part still remain ing insoluble is boiled in concentrated sulphuric acid, for the conversion of starch, etc., into dextro-glucose. Boiling the residue from this treatment with sodic hydrate gives an extract containing albuminous matter, modifications of pectic acid, Fremy's "cutose," coloring, humus, and decomposition products. The crude fiber from this process, treated with chlorinated soda, bleached, and dried, leaves a residue of cellulose. Treatment with benzole, 80 per cent alcohol, and water, removes from nearly all plants the constituents of greatest chemical and medicinal interest. In analyses of food materials the compounds extracted by dilute acids and alkalies have great value.

A NEW DIGESTIVE AGENT.-In a paper before the French Academy of Sciences, M. Wurtz has drawn attention to the great chemical and therapeutical value of a substance called papaine, which possesses the property of exciting the digestive function. It is derived from the juice of the common papaw-tree (Carica papaya), which belongs to the family of the Cucurbitacea, or gourds. The milky juice which contains the papaine is slightly bitter and styptic, free from tartness, but with a weak acid reaction, and is so highly charged with albumen that Vauquelin compared it to blood deprived of its coloring matter. It flows from incisions made in the bark and the green fruits, and is immediately bottled and sent to market, either pure or with the addition of ten or twelve per cent of alcohol to prevent fermentation. If pure, it becomes coagulated; if mixed with alcohol, it remains liquid, and, after standing, separates into a clear liquid and a white precipitate, composed in great part of albumen,

fibrine, and a considerable quantity of precipitated papaine. Alcohol precipitates from it crude papaine; this, after being washed in alcohol and ether, to remove fatty matters, is again dissolved in water. The precipitate from this solution is pure papaine, which, when purified by dialysis, has the composition of an albuminoid substance. Papaine, refined with the subacetate of lead, offers several distinctive characteristics, among which are: 1. It is very soluble in water, dissolving like a gum; 2. The solution makes a lather with water; 3. The solution becomes turbid in boiling, without coagulating; when it is curdy it sometimes leaves an insoluble residue in water; left to stand, the solution becomes turbid after some days, and a microscopic examination shows it to be filled with vibriones; 4. In the presence of a saccharine liquid, papaine acts as an alcoholic ferment with an extraordinary energy and promptitude, but the digestive property may be arrested by the application of benzoic or salicylic acid. The most important property of papaine, and one which puts it in the rank of the most powerful digestive ferments, is its action on meats. One part of papaine will digest and transform into soluble peptone from two hundred and fifty to three hundred parts of meat. Its solubility in different fluids allows it to be used in a great many pharmaceutical forms; and, being a vegetable juice, it can be preserved with more stability than animal ferments, and can be kept indefinitely when dry.

REPORT ON PHOTOMETRIC STANDARDS.-The committee appointed by the British Board of Trade to examine and report upon the different standards of photometric measurement which have been proposed for adoption, as well as upon the standard now used for testing the illuminating power of coal-gas, have made a report recommending the standard air-gas flame of Mr. G. Vernon Harcourt as the most exact and trustworthy. This flame is produced by burning a mixture of air with that portion of American petroleum which, after repeated rectifications, distills at a temperature of 50° C. or 122° Fahr. The portion is almost entirely composed of pentane, and is used in the proportion of one volume of pentane at 60° Fahr. to 576 volumes of air. The flame is brought to a height of two and a half inches with a burner a quarter of an inch in diameter. The light is quite uniform, the extreme difference obtained by two observers in nineteen observations being 0-3 of a candle, or 1.8 per cent. The committee found candles very objectionable as standards, and subject to a maximum variation in 115 determinations of 22.7 per cent between two pairs of candles. Messrs. Keates and Sugg's plan for burning sperm-oil with a two-inch flame from a circular wick was found subject to sudden variations; and Mr. Methven's system of allowing only a particular part of a three-inch coal-gas flame to pass to the photometer was not considered sufficiently exact for the work required of it.

COLOROMETRIC ESTIMATION OF CARBON IN IRON. The great extension which has taken place in the applications of steel has made it desirable to obtain tests for the presence of carbon of a more minute degree of exactness than has heretofore been deemed sufficient. Professor Eggertz has described, in the "Jern Kontorets Annalen," a method of colorometric estimation which is applicable to cases in which an exactness of 0.01 per cent is wanted. The basis of his process is the solution of ferric hydrate in nitric acid, to which a volume of water equal to that of the acid is added; when the quantity of acid used is commensurate with the proportion of carbon in the iron, the yellowgreen color of the solution is cleared on adding an equal volume of water. Care must be taken that no chlorine is present, for the slightest trace of that substance gives a yellowish tint. The quantity of nitric acid required for solution is regulated to a certain degree by the supposed amount of carbon in the iron. For a solution with a lower amount of carbon than 0.25 per cent, 25 c. c. of nitric acid should be used for 0.1 gramme of iron; with carbon of 0-3 per cent, 3 c. c.; with carbon of 0.5 per cent, 3.5 c. c.; and for carbon of 0.8 per cent, 4 c. c. of acid. When the amount of carbon is altogether unknown, begin with 2.5 c. c. of nitric acid, and afterward add more as soon as the color of the solution or the amount of separated carbon shows that more acid is required. Too little acid gives too deep a shade, while excess of acid may be remedied by adding more water. The iron to be tested should be finely divided by filing, boring, planing, or crushing. The solution should be made at 80° C., with shaking of the tube. It is often more convenient to put the tube in boiling water; and speed can be gained at the expense of having a reddish-yellow film to deal with, by gently boiling the mixture. Special normal solutions, for comparison, are prepared in the same manner and graduated by successive dilutions from the normal, which represents 0·10 per cent of carbon per c. c. of 0.1 gramme of iron, and may be used for iron with 0.8 per cent and higher of carbon, down to the normal which represents 0-005 per cent of carbon, and is used for iron with from 0·04 to 0·08 per cent, or the lowest amount of carbon found. The distribution of the light in the room should be considered in applying the test, and it should be observed that a tube held on the right is generally a little weaker in color than one held on the left. The presence of manganese in the iron communicates a brown color, which is changed by heating to 100° C. to a weak redviolet; chromium gives a grayish blue; vanadium, a weak yellow; nickel, a green-all of which colors vanish under a greater or less dilution with water. Cobalt gives a red color which can not be regarded as absent till the dilution has extended to 40 c. c. Phosphorus, sulphur, copper, silicon, in the proportions in which they were tested by ProVOL. XXI.-7 A

fessor Eggertz, did not perceptibly affect the color.

A NEW VEGETABLE COLORING PRINCIPLE. — Messrs. S. P. Sadtler and W. L. Rowland have analyzed a new vegetable coloring matter found in the West-African wood called betha-barra, a wood which is much valued for its extreme toughness and its capability of receiving a high polish. The wood is compact, very heavy, and of nearly the color of black-walnut. On close examination the interstices of the fibers are seen to be filled with a yellow, crystalline powder. In this respect the beth-abarra differs from logwood, barwood, camwood, and red sandal-wood, with which it was compared, in which the color is uniformly disseminated, and the fiber appears as if it had been soaked in a solution of corresponding color. The solution of the coloring matter obtained by extracting from the sawdust or raspings was treated for precipitation with acetic acid, and the pure substance was obtained by successive crystallizations from the alcoholic solution of the precipitate. The material thus gotten is a tasteless, yellow compound, apparently crystallizing in scales and needles, which are found under the microscope to be made up of a series of flat prisms, joined laterally. The crystals are unchanged in dry or moist air, insoluble in cold water, very slightly soluble in hot water, but readily soluble in alcohol and ether; they dissolve with a deep claret-red color in the presence of even a trace of alkali or alkaline carbonate, and melt at 135° C. Analysis gives a composition for the material dried at 125° C. which is represented by the formula C2H22O5, or possibly C22H2O4, and for that dried at 100° C., C28 H29O+3H2O. The beth-a-barra presents a similarity in many of its reactions leading to the suspicion of a relationship with chrysophanic acid and chrysarobin.

ACTION OF SEA-WATER ON CAST-IRON.-Professor A. Liversidge, of the University of Sydney, has made a study of the action of sea-water on cast-iron in the case of the screw of the steamdredge Hunter, which became so rotten that it had to be removed. Even on the most cursory examination the specimen was seen to differ entirely from the original cast-iron, except in its shape, which remained unchanged. The material was so altered in composition that it might be safely described as a pseudomorph, since it was almost entirely made up of oxide of iron and particles of graphite. It was quite sectile, being readily cut with a knife. The powder under the microscope presented a mixture of brilliant scales of graphite with browncolored oxide of iron and a few widely scattered minute particles of metallic iron. The external part of the specimen was of a dull-gray color, while within it was rusty brown, with dark bands following more or less closely the outer contour lines. The specific gravity was found to be only 1.63. Phosphorus appeared to have been completely eliminated by the

action which had gone on, and the amount of sulphur was quite small. Several notices of a similar transformation of cast-iron into graphite occur in the annals of chemistry, the oldest one dating as far back as 1740. Wrought or malleable iron does not appear to be subject to it. The plumbaginous masses thus formed frequently but not invariably become red hot and spontaneously inflammable on exposure to the air. The transformation is attributable to the local galvanic action set up between the diffused scales of graphite, films of slag, or other foreign matter contained in the iron. The coating of plumbago and rust is negative to the metal, and hence if left on assists in further corrosion; but the rate of corrosion, according to the observations of Mr. Robert Mallet, appears as a decreasing one when the coating first formed is removed prior to a second immersion. When cast-iron is exposed to the combined action of fresh water and seawater, the action is said to be much more rapid, for the heavier sea-water below, and the lighter fresh water above, with the iron, form a voltaic pile having two liquids and one solid.

A NEW MINERAL, Beegerite.-Mr. George A. König has described and analyzed a new mineral from the Baltic lode of the Geneva Mining Company, Park County, Colorado, to which he has given the name of beegerite. The specimen on which the investigation was made was composed of quartz, about one half, and the new mineral in the two conditions of a light gray mass, and of crystals showing a darker gray color but exhibiting a very strong metallic luster, which were chemically identical with the gray mass. Beegerite forms minute crystals of orthorhombic habit; has a specific gravity of 7·273; acts before the blowpipe like a mixture of galenite and bismuthite, with a small quantity of copper, and decrepitates; and is dissolved by concentrated hydrochloric acid, slowly in the cold, but rapidly in the heated acid. The analyses gave it a composition represented by the formula, Pb. Bi, S6 PbS+Bi2Ss, with some copper. The compound exhibits properties nearly coinciding with those of galenite, and is qualitatively related with the two species, cosalite and schirmerite.

THE ALKALOID of Piturie.—Professor Liversidge, of Sydney, New South Wales, has extracted the alkaloid principle of piturie, a vegetable substance obtained from a species of Duboisia, of the order Solanacea, which is chewed by the Australian natives, and exerts an action similar to that of tobacco. Baron von Mueller and M. A. Ladenburg had previously experimented with the alkaloid, but their accounts of it do not agree. As prepared by Professor Liversidge, by distillation of the plant with caustic soda, solution in ether, and removal of the ether by distillation, the alkaloid, piturine, is at first clear and colorless, but becomes yellow and finally brown with access

of air, especially when exposed to sunlight. If air is excluded it will remain unchanged for a long time. It is soluble in all proportions in water, alcohol, and ether, yielding colorless solutions, and produces a greasy stain on paper, which disappears after a time. It is a little heavier than water, is volatile at ordinary temperatures, giving a vapor which forms a dense fog with hydrochloric acid, irritates the mucous membranes very much, and induces violent headaches in those working with it. Its taste is acid and pungent, and very persistent; its smell when fresh is very like that of nicotine, but after it has become darkened is more like that of pyridine. It neutralizes acids completely. Its composition is represented by the formula C&H.N14.

CULTIVATION OF NITRIC FERMENTS.-Mr. R. Warington has communicated some preliminary results of a course of experiments he has been making on the conditions in fermentation which respectively determine the formation of nitric and nitrous acid. When a small quantity of fresh soil is employed to seed solutions of chloride of ammonium supplied with nutritive ingredients, a pure, or nearly pure, nitric fermentation is obtained if the solution is sufficiently shallow and dilute, and the temperature low. Under such circumstances only a trace of nitrous acid is formed, and this changes into nitric acid before the conclusion of the action. If the solutions employed are much more concentrated, or the temperature is considerably raised, large quantities of nitrous acid are produced. In all cases in which soil has been used as seed, the nitrous acid exists only temporarily in the solution, the final product of the fermentation being always nitric acid. Soil added to a solution of nitrite of potassium, supplied with nutritive ingredients, readily converts the nitrite into nitrate. When solutions which have been seeded with soil and have undergone the nitric fermentation are themselves employed as seed for new solutions of ammonia, the final result as before is nitric acid, provided the solution used as seed is only a few months old. With older solutions the result of the fermentation is apparently only nitrous acid, which does not further change into nitric acid, except when, as sometimes occurs, a white organism, a bacterium, after a considerable time, appears on the surface of the liquid, and spreads, under favorable circumstances, to cover it. When a solution which has undergone the nitrous fermentation is used as seed, it again produces a purely nitrous fermentation. These results accord with the fact noticed by Pasteur, that the energy of infectious organisms may be reduced by cultivation. The nitrifying ferment appears, then, to exist in the three conditions of the nitric ferment of the soil, producing nitrates; the altered ferment producing nitrites; and the surface organism, which changes nitrites into nitrates.

RELATIONS OF BACTERIA AND VARIOUS GASES. -Mr. F. Hatton has made some experiments to

arsenic in considerable proportions-the pink, which had the least, having enough on a square foot to poison an adult person. By the side of these papers were placed, for comparison, six other samples obtained from another manufacturer, the colors of which could hardly be distinguished from those of the arsenical papers, but which were wholly free from arsenic. From these and other papers which were compared with the same object, it was found that almost any color that may be desired can be obtained without the addition of that substance. If any difference exists in the appearance of the arsenical and non-arsenical colors, it is that the former are rather brighter. This, however, is not altogether a merit, for wall-colors may very easily be too bright. It is still undetermined whether the cheaper or more expensive papers usually contain more arsenic, and also in which class it is more commonly found.

AMMONIA IN HUMAN SALIVA.-Mr. B. H. Heyward, of the laboratory of the University of Virginia, has made some researches into the presence of ammonia in human saliva. Evidence of the presence of the alkali was obtained by observing the action of heated oxide of magnesium upon filtering-paper moistened with the Nessler reagent. The paper showed a distinct orange tint when saliva was present, but was not affected when the saliva was omitted. In all of nineteen different cases examined, of as many young men in good health, the ammonia reaction was obtained. In ten of the cases the amount was approximately determined to be in proportions varying from thirty to one hundred milligrammes of ammonia per litre of saliva. The proportions in the mixed saliva of a single person varied, on seven successive days, between forty and sixty milligrammes per litre. Special experiments directed to the different salivary glands indicated that most, if not all, of the ammonia came from the parotid and submaxillary glands, the latter furnishing notably the larger share, and that the source of ammonia-at any rate, the sole or chief source-is not to be found as free gas in the expired products of respiration condensed in aqueous solutions in the mouth.

GUM-LAC FROM ARIZONA.-A resinous substance has been found widely distributed throughout Arizona and Southern California, where it forms a coating of considerable thickness on the twigs of the Larrea Mexicana, or greasewood," which exhibits the cellular cavities containing ova of insects, and at certain seasons a red fluid, and other characteristic properties as to color, solubility, the color given to different solutions, action under the influence of heat, and odor, of the gum-lac of India. An analysis of the substance, by J. M. Stillman, of the University of California, gives its composition as consisting of 617 parts of resins, 14 of coloring matter soluble in water, 26-3 of caustic potash extract, 60 of insoluble residue, with a loss (including some coloring matter) of 4.6.

This shows a near correspondence, as to essential elements, with the composition of the Indian shellacs. A gum is also found, but in smaller quantities and having a less amount of coloring matter, on the twigs of the Acacia Greggii, which resembles the lac from the Larrea in its general appearance and irregular cellular structure, as well as in its essential chemical properties, and behaves in the same manner toward chemical reagents.

THE FREEZING-POINT OF ALCOHOLIC MIXTURES.-Researches which have been made by M. Raoult, of the Faculty of Sciences at Grenoble, on the point of congelation of alcoholic liquors, show that the point at which mixtures of alcohol and water begin to freeze falls as the proportion of alcohol becomes stronger. M. Raoult has made a table of the points of congelation for different mixtures, by a comparison with which the strength of any given mixtures may be determined by subjecting them to the freezing-test. Fermented liquors congeal at a temperature a little lower than mixtures of alcohol and water of the same strength, the difference increasing as the proportion of alcohol becomes stronger. In all cases the ice consists of pure water, wholly free from alcohol. Hence the part of the liquid left unfrozen is richer than the original liquid, and it follows that the point of congelation descends as the congelation progresses.

A NEW THEORY OF STEEL.-Mr. W. Mattieu Williams has proposed a new theory to account for the temperability of steel. It is well known that, if steel is heated red-hot and suddenly cooled, it becomes extremely hard and brittle; if heated again and slowly cooled, it becomes almost as soft and tough as wrought-iron. If it is moderately heated, it becomes partially softened or "tempered," in proportion to the temperature to which it is raised. None of these properties is possessed by either of the materials, carbon or iron, of which the steel is composed. Mr. Williams's theory is based on the fact that there exists a definite compound, consisting of four equivalents of iron to one of carbon, which may be obtained in crystals, and which is more fusible than ordinary steel, and far more fusible than iron, and is excessively hard and brittle, but not temperable like steel. When it is melted at a temperature at which iron is quite infusible, it is capable of dissolving iron, and forming a liquid mixture. When such a mixture is cooled below the solidifying point of one of the substances, while its temperature is still above that of the other, then one must be still fluid while the other is striving to solidify. "If the cooling beyond this goes on slowly, the molecular conflict will have time to settle itself; but, if the cooling is ef fected suddenly, there must be a 'molecular strain,' due to the inequality of contraction of the different parts of the solid and the liquid portions of the mixture, the internal fluid movements necessary for the adjustment of this irregular contraction of the different parts