124 THE ANALYST. ON THE ESTIM.ATION O F ETHYL NITRITE IN SPIRITUS ETHERIS NITROSI, B.P. BY JOHN MUTER, PH.D,, F.C.S. I HAVE been in the habit of using a saponification process for this spirit, but I work in n manner somewhat different from that used by Dr. DuprB, which I think possesses several advantages. (1). Decinormal solution of hyposulphite of soda (sodium thiosulphate), m d e exactly according to the directions of tlie British Pharmacopmia, each C.C.of which = .0127 free iodine. Solution of potassium permangnnate, containing 3.175 grammes per litre, and checked to balance the ‘( hypo.” solution, by adding excess of saturated solution of potassium iodide to 100 c.c., and then seeing that the iodine set free exactly requires 100 C.C. of 6chypo.” for complete decolourisatioii, starch paste being added as an indicator towards the end of the process.I first take the specific gravity of the saiuple at GOQ Fnlv,, and I then measure out The solutions I use are : - (2).THE ANALYST. 125 10 C.C. of the spirit for analysis. This I digest with sufficient potassiluu hydrate in a small strong glass flask, closed by a cork, through which passes a bent delivery tube, dipping under a column of mercury in a test tube, of such a height as will enable me to lieat gently on a water-bat11 u d e r pressure without bursting the flask.This point is ascertained by a blank experiment, during wliich the flask is wrapped in a cover to prevent accident ; and oiice arrived at, the same flask and mercury column are always employed.After digestion under pressure witli frequent agitation for some time (an lioru. being usually ample), water is added, aucl the contents of the flask eraporated iii a basin until no smell of spirit is perceptible. The residual liquid having been rendered just w x t r d with sulphuric acid, is filtered into a flask containiiig 75 C.C. of perrnan- ganate solution, previously dilated to 200 C.C.with water and acidulated with 20’ C.C. dilute sulphuric acid (1 in 3), and the flask having been corked is left for half an hour. At the end of that time excess of saturated solution of potassium iodide is added (which should produce a clear deep orange solution), and the whole brought under a burette containing the hyposulphite solution and titrated. The number of C.C.of ‘‘ hypo.” used is deducted from the number of C.C. of permnnganatc put in, and the differciice mdtiplied by e00375 gives the amognt of ethyl nitrite in the 10 C.C. taken for analysis, aiicl if tliis be multiplied by 100 and divided by 10 times the specific gravity of tllc original spirit, the answer will be tlie percentaige of etliyl litrite by wcight. In ~ ~ r l i i l l g with spirits of ~ulkiiox711 strength it is advisable to put only 20 C.C.of permanganate into tlie flask at first, diluted and acidulated as directed, and then if all the colour disappears under five miiiutes, to add 5 C.C. more at a time, until a permanent colour is obtained, lasting five minutes, .when the addition of another 5 C.C. will suffice before setting asidc for the lialf hour.In a good spirit it is sufficient to take 5 C.C. for analysis, and to usc 35 to 38 C.C. permaiigaiiate. I am the more inclined to believe in the accuracy of this metllod, because I have found, by expiment, tliat the action of potassium nitrite on permanganate is iiot thoroughly trustworthy under lialf an hour, I3 thy1 nitrite is, however, much uorc mpiclly affected, and I am at present cngagel on a process whereby saponification is eiitirely avoided, aiid the whole thing docs not occupy more than ten minutes.Tj’atil I publish this, I reserve my results on tlie actual constitution of the spirit, alld the loss it uiidergoes by keepiizg. I am not at all clear that we should depend entirely on the etliyl nitrite alone for the real value of tliis rncdicine, and my other method depends on the estimation of tlie aldehyci and other boclies present in the article when pyoperly made according to the official process.The following are some analyses of pure spirits (specially made for ine by Mr. Phillips-of Messrs. Iiiioivles and Phillips-strictly by the B.P. process, and answering the gravity and separation tests of that authority), which were recently performed by one of my advanced stde11ts, MY. Lather Scammel1:- Saiiiplc No.1 contsbined 3.03 ethyl nitritc 7 7 7 9 2 7 7 ‘L.91 7 , 9 7 7 , 7 , 3 - 7 2.96 ? I 7 9 3 7 ,, 4 7 7 2-35 7 , 1 9 9 , 9 , 5 3 9 2.39 $ 3 9 , 9 7 ,9 7 7 2-93 ,, ,,126 THE ANALYST. I always prefer prefer to do a blank experiment, using 20 C.C. pure rectified spirit, and the same weight of potassium hydrate as I use to the ether, and check it side by side with the sample experiment. In practice I use about two grammes K H 0 aiid add 10 C.C. of rectified spirit, which sicis its solution and helps saponification of the ethyl nitrite. I have also often used, for the sapoiiification, a small flask fitted to a well cooled upright condenser, a i d worked at the boiling point ; but I find the simple arrmgement above stated does just as well.