View Article Online / Journal Homepage / Table of Contents for this issue ii. 294 ABSTRAOTS OF CHEMICAL PAPERS. Bnelytical Chemistry. Colorimetric Determination of the Hydrogen-Ion Concentration in Small Quantities of Solution. A. R. C. HAAS(-7. 13id. Ch~ni., 1919, 38, 49--55).-The preparation of indicator papers which niay be used for the rapid estimation of hydrogen-ion concentration is described. The method yields accurate results, and is of considerable value when it is impossible to carry oiit the electtrometric method. J. C, D. Accuracy of Different Methods of Measuring Small Volumes of Fluid. FREDERICKWILLIANI AND RE WE^ (Biochem. J., 1919, 13, 37--44).--R study of the inaccuracies atteiidaiit on the methods employed for nieasurement of small volumes and dili-itions, such as are1 uped in serolngical investigations. 5. C. D. Preparation of Stable Starch and Oxalic Acid Solutions by means of Metallic Mercury. A. JUNK(Ghem. Zeit., 1919, Published on 01 January 1919. Downloaded 27/10/2014 15:30:12. 43, 258).--The solution is treated with a few C.C. of mercury, boiled, and shaken, so that the mercnry is finely subdivided; the mercury is allowed to remain in the bottle containing the solution. Such treatment prements the growth of moulds, etc., in the solutions, and the latter may be kept for years without altering in strength, even when the1 bottle is opened frequently. M7. P. s. Identification of Iodine in Blood by a Microcrystal- lographic Method. ULRICHHINTZELMANN (Zeitsch. physiol. Cheuz., 1919, 104, 211---216).-The method proposed by Karfunkel (BeiLt. n?cd. Tl'orh., 1912, 643), which depends on the isolation of crystals of iodohmnatin, is untrustworthy for ordinary use. J. C. D. Modification in the Technique of Fischer's Reaction for Hydrogen Sulphide. LUCIANOP, J. PnLm and ANANCIO FERNANDEZ(91ial. SOC. Quim. ,-Zrgentiritc, 1918, 6, 49--51).-0n account of the incoiivenience in prepariug and keeping p-arnino- dimethylaniline sulphate, the following procedure is substituted. View Article Online ANALYTICAL CHEMISTRY. 3. 295 To a drop of dimethylaniline are added 2 c.e. of water, three to four drops of a 1% solution od sodium nitrite, and five drops of 10% hydrochloric acid. The liquid is neutralised with saturated sodium carbonate solution, and the nitroso-base extracted with ether. To the ethereal solution, zinc powder and a few drops of concentrated hydrochloric acid are added. TT7hen the reduction is complete, tthe ether layer is decanted off. 2 C.C. of water and the solution to be tested are added, then concentrated hydrochloric acid, and a few drops of 1096 ferric chloride solution. The addi- tion of a little alcohol renders the appearance of the resulting methvlene-blue moce distinct. It is necessary that hvdrochloric acid be present' in gpat exceqs. W. S. M. Estimation of Sulphuric Acid and Sulphates. G.MEILLBRE (-7. Phm177. Chim ., 1919, rvii], 19, 296--397).---In the estimation ol€ sulphates by precipitation as barium sulphate, the precipitate should be collected while the solution is still hot and washed with hot dilute acetic acid solution. In the case of sulphuric acid. this may be neiitralised with barium hvdroxide solution, using phenol- phthaleiii as indicator, and a very slight excess of the bariiim hvrlr- oxide then added; the mixture is acidified with acetic acid. kept at 100° for two hours, and the precipitated barium sulphate then collected. [See, flirther, .7. ,COP. Phrnr. JII~.,1919, Julv.1 w. P. s. Method for the Volumetric Estimation of Sulphates . A. C. D. RrVETT (Chtvu. .!TTew.'i, 1919, 118, 253--254).---The method is intended prirnayily for works purposes? and depends on double decomposition between moist, precipitated barium osalate anti certain dissolved sulphates, whereby soluble oxalates are pro- Published on 01 January 1919. Downloaded 27/10/2014 15:30:12. dnced which may be titrated with potassium permanganate. [For details, see .7. ,Yw.PJi~n7, 7nc?., 1919, 481 A.I W,E. F. P. Continuous Process €or the Estimation of Nitrogen by Dumas's Method, TAJDWIC, DEXHEIMER(Zeitsch. anal. Chenz., 1919, 58, 13---19).--To1 avoid the necessity of cooling the combus- tion tube after the completion of one estimation and before another can be started, a procedure is described for removinq and inserting success;ve boats while the tube is ?till hot. The essential feature consists of means for passing the current of carboii dioxide in a reverse direction through the tube while the latter is opened at one end. Provision is also made for oxidising the reduced copper when necessary. TN. P. s. The Estimation of Total Nitrogen in Soils containing Rather Large Amounts of Nitrates. R. 5. SNYDER(Soil Sci., 1918, 6, 487--490).--If the organic matter of the soil is within the usual average (0.8--3*0%), the Hibbnrd or the "mercury" methods of carrying out the Kjeldahl digestion give quite1 accurate View Article Online ii. 206 ABSTRACTS OF CREMICAL PAPERS. results for total nitrogen, even if 10% of the nitrogen is present as nitrate. Methods for total nitrogen, modified to include nitrate nitrogen, such as Ulsch’s method, must, however, be used if the organic carbon content of the soil is lower than 0.5%. W. G. Estimation of Nitrite and Nitrate Nitrogen in the Presence of other Nitrogen Compounds. TH. PFEIFFERand W. SIMMERMACHER(Landw. 7*ersttchsstat., 1919, 93, 65-76).- For the estimation od the various forms of nitrogen in such sub- stances as soil extracts, the total nitrogen other than nitric nitrogen is estimated by Kjeldahl’s method, using 5 grams of ferrous sulphate. Ammonia nitrogen is estimated by distillation with magnesium oxide; after the ammonia has been removed, the resi- dual solution is treated with 12 grams of magnesium chloride and 3 grams of finely divided copper-magnesium alloy (compare A., 1917, ii, 504), and again distilled to obt,ain the ammonia derived from the nitrites and nitrates. To estimate the nitrate nitrogen, 75 C.C.of the extract are boiled for one hour with the addition of 1.5 <gramsof dextrose, 0.3 gram of ferrous sulphate, and 5 grams of sodium carbonate: ammonia and nitrite nitrogen are thus ex- pelled, and the solution is then distilled with copper-magnesium alloy as described. [See, further, .7. SOP.Chw. 7t7d., 1919, Julv.] w. P. s. Scrubber €or Ammonia Distillations. B. S. Davisso~ (J. Iud. Enq. Chem., 1919, 11, 465--466).-The scrubber or still- head described consists of a bulb of about. 200 C.C. capacity pro- vided with an exit. tube at the top, through which the steam, etc., passes to the condenser, and a lower tube or stem for connecting t(he bulb to the distillation flask. This lower tube extends into the bulb, and is then bent downwards to nearly the wall of the Published on 01 January 1919. Downloaded 27/10/2014 15:30:12. bulb; the, tube ends in a small bulb having three openings in the same horizontal plane. The first’ portion of steam which enters the bulb condenses, and the water flows down about the small bulb, there acting as a scrubbing solution for the remainder of the va paurs. w. P. s. Albuminoid Ammonia Test. EVELYNASHLEY COOPER and JOSEPHALAN HEWARD(Biochen~. J., 1919, 13, 25-27).- Potassium perrnanganate may co’ntain a stable nitrogenous impurity which cannot, as a rule, be removed by prolonged boiling with alkali. This impurity yields ammonia, particularly when the permanganate-alkali mixture is boiled in the dilute condition, and the error involved may be so great as to vitiate the value of the albuminoid amnioiiia test altogether. [See, further, J. SOP.(71i~m. Jltd., 1919, 438A.1 J. C. D. Identification of Arsenious Acid Reply to Tunmann. R. WASICKYand A. MAYRROFER(Pl2nnn. Post., 1918. 51, 409-410; from Ch~m.Zfnfr., 1919, ii. 324).--The authors do not agree with Tunrninn’s observntions (A., 1918, ii. 453) on the View Article Online ANALYTlCAL CHEMISTRY. ii. 297 extension of microchemical methods to the detection of arsenic in pharmaceutical preparations, and, further, point out that the destruction of organic matter by concentrated sulphuric acid on the object-glass does not suffice for the detection of arsenic in all possible forms of combination. H. w. Estimation of Boric Acid. PAULJANNASCH and FRIEDRICH NOLL(J. pr. Chem., 1919, Lii], 99, 1-33).-Alcoholic sodium ethoxide solution is recommended for the titration of boric acid solutions in the presence of glycerol ; the interfering action of carbon dioxide is thus eliminated. For the estimation of boric acid in minerals, the sample is fused with sodium phosphate and metaphosphoric acid, the boric acid distilled in the presence of inethyl alcohol and phosphoric acid, and titrated after the methyl alcohol has been expelled from the filtrate. [See, further, J. Soc. C'hcru. Id., 1919, 411~.] w. P. s. Estimation of Free Carbon Dioxide in Water. HARTWIG KLUT(Ber. deut. pJhart/2. G'es.., 1919, 29, 344-359).-Directions are given for the estimation of free carbon dioxide in water at tho source of the latter. The titration is made with sodium carbonate solution, phenolphthalein is used as the indicator, and potassium sodium tartrate is added to the water to prevent interference by ferrous salts. w. P. s. Estimation of Free Carbon Dioxide in Water. RUDOLF CZENSNY(Zeitsch. ctnwl. Chei)c., 1919, 58, 1--12).-To ensure that the correct quantity of indicator is present, a combined solution containing 2.6525 grams of sodium carboiiato and 2.5 grams of phenolphthalein is used for the t.itration of the free carboii dioxide. Published on 01 January 1919. Downloaded 27/10/2014 15:30:12. One hundred C.C. of the water are titrated with this solution; the number of C.C.used, less 0.52 c.c., is multiplied by 1-22 to obtain the mg.