TPHE ANALY8T. 115 A METHOD OF DETERMINING ORGANIC NITROUEN IN LIQUIDS. BY A, WYNTER BLYTH, M.R.C.B., F.I.C. &dd 60fOTS th6 SOOiCtj/ Of pU6& h d 3 l 8 t 8 , OB &&I% I8?%, 1884. THE method of oxidation by means of sulphuric acid in excess and permanganate of potash is not a new one. The prooess in its details, nevertheless, was recently muoh improved by Vijeldahl (Zeits fur Analytische ohemie Hefl. 3, 1883 ”) and proposed by him as a m o a process of oombustion. Still more recently Ilr. Petri and Th. Lehmann (‘I Zeitsdh fur Physiologische Chemie, Band VIII., Hefl. 3, 1884 ”) have pub- lished an account of an extremely prolonged aad exhaustive reeearoh, as to its accuracy in determining the total nitrogen in urine ; and have somewhat improved the details. I contributed in April of this year, to the Royal &oiety, a paper on the ingests and egesta of Edward Payaon Weston, and gave incidentally, a biie€ description of this method whiohI had applied with great advantage to the estimation, day by day, of the total nitrogen of the pedestrian’s urine, as follows :- Two grams of the urine were placed in a && and 20 cubic aentems of pure adphuric aoid added; heat was applied by means of a small flame for two or three hours, at the end of whicIi time c r y s a of permanganate were added until the liqGd was first decolouriaed, and then given a distinct dark pink or red tint.On now alkdising with pure oxide, a l l the nitrogen present was distilled over &B ammonia; the distillation being assisted by a current of hydrogen gas, the ammoniacal distillate was received in a known quantity of standard decinormd acid and titrated back by deci- normal soda.I have since made a number of analyses of flour and farinaceous foods, and compared four of them with combustion processes, and the resdts have been eminently satisfaotory. 1 have also applied it to malt extract in solution, to cocoa, to tea and to coffee. Two analyses of water have been made by this moist procese ; the result was such as from the general character of the water might be expected, but no check combustion was made, SO I am ignorant tzs to how the two methods would compare.116 !EiX ANALPIST. ~ -~ It seems to be so extremely convenient and its applications so numerous, that any analyst would confer a bendti on us all, if He should make a number of comparative determinations of the total xGtrogen in water, milk, broth, $c., and commzznicElte the results to the Society. The sdphuriio aoid S have med, has never been absolutely ammonia free, but it wm found easy to make blank experiments and get out a constant factor, but with such a strongly nitrogenous liquid as urine, even this mas not necessary, tho orror falling in the third deoima;2 plaae ; on the other hand, in the case of waor analysis, an exad correotion €or the ammoniwal impurities will of course be important. CON~L~~SIO~; OF TEE PROOEEDINGS OF THE SOO~ETY OF PUBLIU ANALYSTS.