THE SEP 115 MICH CHEMICAL NEWS Edited by AND JOURNAL OF PHYSICAL SCIENCE James H. Gardiner, F.C.S. ] Established (WITH WHICH IS INCORPORATED THE "CHEMICAL GAZETTE"). in the Year 1859. Published Weekly. Annual Subscription, free by post, 1. Entered at the New York Post Office as Second Class Mail Matter. Transmissible through the Post-United Kingdom, at Newspaper rate; Canada and Newfoundland, at Magazine rate. Vol. 119.-No. 3094 [Copyright ARTICLES CONTENTS. Friday, August 1, 1919. Nitrogen and other Compounds in Rain and Snow, by J. E. PAGE CE Aa Alignment Chart for the Solution of Molecular Weight and 49 49 51 53 On the Photographic Spectra of Meteorites, by Sir W. Crookes.. Registered as PRICE 4d. a Newspaper. POST FREE 44d. HEMIST BUSINESS for DISPOSAL as The a going concern, owing to the death of Proprietor. premises are situated in centre of leading city, north of Ireland. Shop handsomely fitted; large Stock. Rent 27 per annum.-Address, L G. C., CHEMICAL NEWS Office, 16, Newcastle Street, Farringdon Street, London, E.C. 4. LABORATORY wanted in London, with or without ANALYTICAL PRACTICE. Send particulars.Address, "Bunty," CHEMICAL NEWS Office, 16, Newcastle Street, Farringdon Street, London, E.C. 4. If in good condition, Sixpence per copy will be paid for any of the undermentioned numbers of the CHEMICAL CAPPER PASS & SON, Lim., NEWS which may be forwarded to this office : BEDMINSTER SMELTING WORKS BRISTOL, WHATMAN'S WHATMAN at free Seamle IN QUALITY TELLS. Aug. 1, 1919 N experiments, the quality of every detail tells. Filter Genuine Whatman Filter Papers are made in all grades- Genuine Whatman Extraction Thimbles are Fat-Free and Seamless. 4 THE importance of analysing the rain and snow for nitrogen and other compounds is widely recognised, both for its agricultural and hygienic significance. Messrs. F. T. Shutt and R. L. Dorrance, of Ottawa, Canada, carried on a systematic investigation of the rain and snow covering a period of ten years, 1908-1917, the results of which have added much to our knowledge of the importance of the nitrogen compounds as an agricultural factor. Our purpose has been to determine the amounts of the different nitrogen compounds, the chlorine, sulphates, and phosphates, in the rain and snow of this locality-a con tinuation of the work which has been carried on here for a number of years, the results of which have appeared in the CHEMICAL NEWS from time to time. The work was carried out in the Cornell College laboratories under ordinary laboratory conditions. It covers a period of eight and a half months, October 1, 1918, to June 15, 1919. The samples were collected in granite pans on an open spot near the centre of the town, which has a population of about 2500. The town is without manufacturing industries, which eliminates excessive smoke contamination of the air. Every precaution was taken to prevent contamination. Samples were collected imme. diately following the precipitation, and analysed as soon thereafter as was possible. Altogether 46 samples were investigated, of which 36 were rain and 10 were snow. This represents 22:25 inches of rain, considering 12 inches of snow equivalent to I inch of rain. The precipitation has supplied during the period 511-74 pounds of chlorine equivalent to 842 15 pounds of sodium chloride; also 1'509 pounds of sulphates as SO3, and 5.2790 pounds of nitrates per acre. The phosphates as P2Os amounts to only o'0086 pund per acre. Only 15 samples produced sufficient sulphates for deter. mination, the highest of which, on February 28, contained 0-262 part per million; and only 11 other samples showed a slight trace. The average for the period is 003 part per million. An unusually mild winter, with the atmosphere comparatively free from smoke and soot, possibly explains this low average. Five samples showed a trace of phosphate, while only four supplied a sufficient quantity for determination, the highest of which, on March 4, was only o 03 part per million. The average is 0·002 part per million. albuminoid ammonia, 24'42 per cent nitrates, and 1.74 per cent nitrites. The The amount of the precipitation determines largely the total number of pounds of nitrogen supplied per acre. Yet an examination of the pounds of nitrogen supplied per acre by each of the 46 precipitations reveals a remarkable uniformity. When reduced to pounds per acre for one inch of rain, 43 of the 46 precipitations come within the narrow limits of o 15 to 0.40 pound per acre. wide variation in the amounts of rain, o'05 to 2 inches, indicates a marked degree of concentration in the smaller showers. The same standard reveals that during continued precipitations, as occurred June 1 to June 6, the total nitrogen supplied gradually diminished, in this case from 0'40 to 0.20 pound per inch of rain. There is a gradual increase in the amount of precipitation from October to o 50 of an inch, to June with 4.6 inches for the first half of the month. Beginning with February, there is a gradual increase of total nitrogen in parts per million o 699 to 1134 This with the increased amount of rain in inches, furnishes an increasing supply of nitrogen per acre to the soil during The increase in pounds per the main growing season. acre during this period is from 0.3057 pound in November to 13078 in June. The 45 inches of snow supplied 13 per cent of the total 52790 pounds of nitrogen per acre, or o 6911 pound. The rains supplied 87 per cent or 4.5879 pounds per acre. The rain is shown to be richer in total nitrogen content than the snow. The work of Messrs. F. T. Shutt and R. L. Dorrance, mentioned above, has been of assistance in summarising the results. Grateful acknowledgment is made of valuable assistance AN ALIGNMENT CHART FOR THE SOLUTION OF MOLECULAR WEIGHT AND VAPOUR DENSITY PROBLEMS. By LESLIE J. HARRIS. A VERY frequent method of estimating the molecular weight of a volatile substance is by means of a determination of its vapour density. It was pointed out by Avogadro in 1811 that if, as his hypothesis asserts, equal volumes of different gases under the same conditions of temperature and pressure contain the same number of molecules, then the molecular weights of these gases are proportional to their densities. Avogadro further showed that the molecule of hydrogen contained at least two atoms; he assumed that it contained two only, and not more. Hence its molecular weight was 2, and the densities of gases referred to hydrogen as unity when doubled gave directly the molecular weight. Subsequently it was shown by Kundt and Warburg that the molecule of mercury was monatomic, and this served to confirm Avogadro's assumption as to the diatomicity of hydrogen. Since 2 grms. of hydrogen occupy at S.T.P. 22 234 litres, the weight of any other gas occupying the same The average of total nitrogen supplied for each preci-volume will be its molecular weight in grms. compared pitation is 1.046 parts per million. The totals for the 46 with the standard H2=2. It is now, however, the general precipitations are fairly constant. Strong wind and practice to refer molecular weights to the standard O2 = 32. severe electrical discharges on March 6, and on June 1 On this scale the M. W. of hydrogen is 2 016. This weight and 3, did not increase the amounts of nitrogen, but the of the gas in grms. and therefore the molecular weight of total nitrogen supplied on these dates is unusually high, any other gas, will occupy at S.T.P. 22 412 litres. especially on May 6 and 7, the highest of the period. The chlorine content averages 11'12 parts per million, varying from 6.10 to 25.70 parts per million. Its presence in the atmosphere has been ascribed by Dr. N. Knight to salt particles carried by the winds from the Atlantic Ocean. No increase was experienced due to wind preceding or accompanying a precipitation. The average part per million for free ammonia is 0'407; for albuminoid ammonia, 0.366; for nitrates, o'255; and for nitrites, o'018. Of the total nitrogen supplied during the period, 38.85 per cent is in the form of free ammonia, 34 99 per cent If W grms. of a vapour have a volume at o° and 760 mm. of V litres, its molecular weight m will be given by the formulaW × 22°412 V m and its density D compared with 0= 16 by— W X 11'206 D: V Often the vapour density of a gas as determined in experimental work is compared with air as unity and then multiplied by a constant factor to give its M.W. To save the labour of calculation the writer has devised the alignment chart shown, whereby the molecular weight or vapour density can be read off directly from the weight and volume. Alternatively the weight of a given volume or the space occupied by a given weight of gas may be determined provided the density be known. The chart is read by means of a straight edge (as of a ruler) or a stretched thread, or most accurately by a line engraved on a celluloid cursor. The line is made to coincide with the given values on two of the scales; the point of intersection on the third scale shows the required figureweight, volume, density, or molecular weight, as the case may be. THE RELATIVE STABILITY OF HALOGEN SUBSTITUTED ALIPHATIC ACIDS IN WATER SOLUTION.* II. THE PROPIONIC ACID AND BUTYRIC ACID SERIES. By G. S. SIMPSON. IN a recent paper from the Kent Chemical Laboratory of Yale University (Drushel and Simpson, Am. Journ. Sci., 1917, xxxix., 2453), the relative stability of halogen substi tuted acetic acids as determined by the hydrolysis of their sodium salt s was discussed. This article describes the result of a similar investigation of the stability of several halogen substituted acids in the propionic and butyric acid series. Preparation of Materials. The ethyl esters of a-bromobutyric acid and a-bromoisobutyric acid, which were in stock, were readily purified by distillation. All other acids or esters were prepared as described below. The chart is constructed on the same principle as my "nomogram" for the calculation of added water in milk, to the description of which the reader is referred (CHEMICAL NEWS, 1919, cxviii., 99). The scales for weight and volume are divided logarithmically and are of the same relative size, but the former is drawn in a positive (down-chloride obtained was added to absolute alcohol to form a-Chloropropionic ester was made from lactic acid by the method of Loven (Journ. Prakt. Chem., 1884, [2], xxix., 367). Dried calcium lactate was allowed to react with phosphorus pentachloride and the a-chloropropionyl The scale for vapour densities is depressed a further distance log 2 so as to give the valuex molecular weight. The "molecular volume," 22:412 litres, is marked on the left-hand scale. The molecular weights of some common gases are also indicated on the central scale. It should be noted that corresponding standards of weight and volume must be chosen, either grms. and litres, or else multiples or submultiples of both; e.g., mgrms. and cc. If desired the graduations for weight and volume may be drawn on a sliding scale, as indicated in Fig. 2, in which case the alignment is performed automatically. In use the value for volume shown on the lower scale is made to coincide with that for weight on the upper scale; the reading opposite the arrow (at the molecular volume) is the required M.W. Alternatively, with the slide rule in a given position all corresponding values of weight and volume for a specified gas are in coincidence. A chart similar to the above may be constructed to show the molecular weights of dissolved substances in dilute solution, from the depression of the freezing-points and the known coefficients of molecular depression for various solutes. The same applies to the molecular elevation of the boiling point, Ruled logarithmic paper may now be obtained from several dealers, and with its aid the drawing of such charts becomes a simple matter. the ester. After purification the product boiled at 145147°. a-Bromopropionyl bromide was made by adding bromine to dry propionic acid in the presence of red phosphorus according to Zelinsky's method (Ber., 1887, xx., 2026). This was added to absolute alcohol to form a-bromopropionic ester, which, after purification, boiled at 157-159°. 3-Iodopropionic acid was prepared by heating iodine and yellow phosphorus with an aqueous solution of glyceric acid, obtained by the oxidation of glycerin with fuming nitric acid and purification by means of its calcium salt. This method of purification of glyceric acid, suggeeted by Drushel (Am. Journ. Sci., 1915, xxxix., 113), gives a crystalline product which is much more convenient to isolate and wash than the gelatinous lead salt. The iodopropionic acid was obtained as pearly white plates by recrystallisation from hot water. B-Bromopropionic acid was formed by adding an aqueous solution of 8-iodopropionic acid to bromine and subsequent heating according to Richter (Zeit. Chem., 1868, 461). The free iodine formed was filtered off and all excess of halogen was removed by pressing the product on a porous plate. It was purified by recrystallising from petroleum ether giving pearly plates melting at 62°. B-Chloropropionic acid has been made by different methods by several investigators, but in each case a different melting-point was recorded. De Barr (Am. Chem. Journ., 1899, xxii., 336) and Richter (loc. cit.) prepared it by the replacement of iodine of 3-iodopropionic acid in aqueous solution with chlorine. The product was then distilled several times over mercury or silver. Such a procedure might easily give adipic acid according to this equation 2CICH2-CH2COOH+2Ag⇒(CH2-CH2COOH)2+2AgCI * From the Journal of the American Chemical Society, xl., No. 4. |