Part 19 (2/2)

~Champion and Pellet's Method~--This method is now very little used It is based upon the fact that when nitro-cellulose is boiled with ferrous chloride and hydrochloric acid, all the nitrogen is disengaged as nitric oxide (NO) It is performed as follows:--A vacuulass stopper on the tube; a delivery tube that can also be closed, and which dips under a solution of caustic soda contained in a trough, and the end placed under a graduated tube, also full of caustic soda Frorm cotton dissolved in 5 to 6 cc of sulphuric acid is allowed to flow into the flask, which contains the ferrous chloride and hydrochloric acid, and in which a vacuu the taps The solution is then heated, the taps on the delivery tube opened, and the end placed under the collecting tube, and the NO evolved collected The NO gas is not evolved until the solution has become somewhat concentrated Eder substituted a solution of ferrous sulphate in HCl for ferrous chloride Care h to stand the pressure, or it will burst

The same chemists (_Co lycerine:--A known quantity of a solution of ferrous sulphate of previously ascertained reducing power is placed in a flask, acidified with hydrochloric acid, and its surface covered with a layer of petroleulycerine is then introduced, and the flask heated on the water bath When the sa to remove nitric oxide, and the excess of ferrous sulphate ascertained by titration with standard peranate; 56 of iron (Fe) oxidised by the salycerine

~The Schultze-Tieen in nitro-explosives, especially nitro-cellulose and nitro-glycerine--The figure (No 44) shows the general arrange description of theit to my friend, Mr William Bate, of Hayle To fill the apparatus with the soda solution, the gas burette is put on the indiarubber stopper of basin W, and firmly clamped down Then the taps A and C are opened, and B closed When the burette is filled with soda solution half-way up the funnel Y, A and C are closed, and B opened

The arrows show the inlet and outlet for the cooling water that is kept running through the water jacket round the nitroas, raise the nitroas tube frolass dish W and under the opening of the nitro 44 SCHULTZE-TIEMAN APPARATUS]

For the estir 45), washi+ng in with about 25 cc of water by alternately opening clips D and E The air in the flask is driven out by boiling, whilst the air is shut off by the tube _i_ dipping into the basin W, which is filled with the soda lye, and tube K is placed in the test tube R, which contains a few cc of water As soon as all the air is coas jet is taken away (This flaskone, or it will burst) Into test tube R, 25 cc of concentrated solution of protochloride of iron and 10 to 15 cc concentrated hydrochloric acid are poured, which are sucked up into the developing flask _f_ by opening clip E, air being carefully kept fro The clip E is now closed, and tube _i_ is put underneath the burette, and the develop the contents of the flask _f_ When the pressure of the gas in the flask has beco tube begins to swell at _i_, whereupon clip D is opened, and the boiling continued with frequent shaking of the bulb, until no as bubbles rise up into the soda lye, the distilling over of the HCl causes a crackling noise, the clip D is closed, and E opened The burette is again put hermetically on the indiarubber stopper in basin W, and the apparatus is left to cool until the water discharged through P shows the sa jacket) Z If the level of the soda solution in the tube X is now put on exactly the sa the tube X as required, the volume of NO obtained in cc can be read off within 1/10 cc, and the percentage of nitrogen calculated by the usual formula

[Illustration: FIG 45--Decomposition Flask for Schultze-Tieman Method]

The solution of protochloride of iron is obtained by dissolving iron nails, &c, in concentrated HCl, the iron being in excess When the developh a paper filter, and acidify filtrate with a few drops of HCl The soda solution used has a sp gr of 1210 to 1260; equals 25 to 30 B The nitro-cellulose is dried in quantities of 2 grht to ten hours, and then three hours in an exiccator over H_{2}SO_{4} The results obtained with this apparatus are very accurate The reaction is founded upon that of MM Champion and Pellet's en~--This ely used by analysts for the deteranic bodies, more especially perhaps in manures, was proposed by J

Kjeldahl,[A] of the Carlsberg Laboratory of Copenhagen It was afterwards modified by Jodlbauer, of Munich,[B] and applied to the analysis of nitro- explosives by M Chenel, of the Laboratoire Centrale des Poudres, whose rested in the cold with a solution of 12 grrm phosphoric anhydride in 30 cc of sulphuric acid The mixture is kept well shaken until the solution is corradually added, the te kept down until corm of mercury is added, and the process continued in the usual way, according to Kjeldahl; that is, the liquid is distilled until all the ammonia has passed over, and is absorbed in the standard acid The distillate is then titrated with standard ammonia

[Footnote A: J Kjeldahl, _Zeitschrift anal Chem_, 1883, xxii, p 366]

[Footnote B: Jodlbauer, _Chemisches Centralblatt_, 1886, pp 434-484 See also _Arroup is at the moment of solution fixed upon the phenol with the production of mono-nitro-phenol, which is afterwards reduced by the action of the zinc-dust into the aen of the amido-phenol becomes fixed in the state of ammonia M Chenel is perfectly satisfied with the results obtained, but he points out that the success of the operation depends upon the complete conversion of the phenol into the anic compound forms a _clear solution_ in the cold sulphuric acid un-cotton must be very finely divided for successful treat table shows some of the results obtained by M Chenel:--

______________________________________________ | | | | | Total Nitrogen | | Substances analysed |______________________| | | | | | | Calculated | Found | | |_____________|________| | | | | | Saltpetre (KNO_{3}) | 1386 | 1391 | | | | 1382 | | | | 1373 | | | | 1396 | | Ammonium nitrate | 3500 | 3531 | | | | 3490 | | | | 3496 | | Bariulycerol | 1850 | 1845 | | Di-nitro-benzol[A] | 1667 | 1678 | | | | 1657 | | Para-nitro-phenol | 1007 | 1003 | | Picric acid[A] | 1834 |1842 | | | | 1843 | | Ammonium picrate | 2276 | 2263 | | | | 2267 | | Di-nitro-ortho-cresol | 1414 | 1410 | | | | 1398 | | Tri-nitro-meta-cresol | 1728 | 1757 | | | | 1727 | |_______________________|_____________|________|

[Footnote A: Dr Bernard Dyer obtained 1839 per cent for picric acid and 1654 per cent for di-nitro-benzol--_Jour Che 1895]

When Chenel endeavoured to apply Jodlbauer's modification of Kjeldahl's process to the examination of the tri- and tetra-nitrated naphthalenes, he found that good results were not obtainable, because these compounds do not dissolve completely in the cold sulphuric acid It may, however, be used if they are previously converted into the naphthylauiar and Lautemann (_Bull Soc Chim_, vol

iii, new series, p 256) This is rapidly effected as follows:--Twelve grrms of phosphorus in about 15 or 20 cc of bisulphide of carbon, this solution being contained in a flask of 250 cc capacity The flask and its contents are heated on the water bath at 100 C with constant attention, until the last traces of the carbon bisulphide have distilled away It is then cooled, and the iodide of phosphorus is detached fro, but not expelled The next step is to add about 05 to 06 grrently two or three times

As soon as the reaction becomes lively, the contents of the flask are well shaken It is usually finished about one minute after the addition of the water The flask is now cooled, and 25 cc of sulphuric acid, together with 07 grradually added; hydriodic acid (HI) forms, and the temperature of the flaskpart of the operation is as in the ordinary Kjeldahl process

M Chenel has found this process the best for the analysis of the nitro- naphthalenes, and for iun-cotton

Personally, I have never been able to obtain satisfactory results with this process in the analysis of nitro-cellulose, and I ae over the nitroun-cotton

Table giving the Percentages of Nitrogen and Oxide of Nitrogen in Various Substances used in or as Explosives:

Nalycerine C_{3}H_{5}(ONO_{2})_{3} 1850 = 6070 Hexa-nitro-cellulose C_{12}H_{14}O_{4}(ONO_{2})_{6} 1414 = 4642 Penta-nitro-cellulose C_{6}H_{8}O_{5}(ONO_{2})_{5} 1111 = 3650 Nitro-benzene C_{6}H_{5}NO_{2} 1138 = 3739 Di-nitro-benzene C_{6}H_{4}(NO_{2})_{2} 1667 = 5477 Tri-nitro-benzene C_{6}H_{3}(NO_{2})_{3} 1924 = 6322 Nitro-toluene C_{7}H_{7}NO_{2} 1021 = 3349 Nitro-naphthalene C_{10}H_{7}NO_{2} 809 = 2653 Di-nitro-naphthalene C_{10}H_{6}(NO_{2})_{2} 1284 = 4212 Nitro-mannite C_{6}H_{7}(NO_{3})_{6} 2359 = 7737 Nitro-starch C_{6}H_{8}O_{4}(HNO_{3}) 676 = 2218 Picric acid (Tri-nitro-phenol) C_{6}H_{2}OH(NO_{2})_{3} 1834 = 6015 Chloro-nitro-benzene C_{6}H_{3}Cl(NO_{2})_{2} 1382 = 4543 Ammonium nitrate NH_{4}NO_{3} 3500 = Sodium nitrate NaNO_{3} 1647 = Potassium nitrate KNO_{3} 1386 = Nitric acid HNO_{3} 2222 = Barium nitrate Ba(NO_{3})_{2} 1072 =

~analysis of Celluloid~--The finely divided celluloid is well stirred, by means of a platinue nitroen determined in the solution in the usual way To prevent interference froested by H Zaunschirhed quantity of the celluloid in a hed quantity of washed and ignited asbestos, or purate the mass, and afterwards extract the cah: then extract with absolute h, and examine the nitro-cellulose in the nitrometer

~Picric Acid and Picrates~--Picric acid is soluble in hot water, and to the extent of 1 part in 100 in cold water, also in ether, chloroforlycerine, 10 per cent soda solution, alcohol, amylic alcohol, carbon bisulphide, benzene, and petroleu solution of potassiu to the formation of potassium iso-purpurate, which crystallises in sreen lustre

This, by reaction with aives ammonium iso-purpurate (NH_{4}C_{8}H_{4}N_{5}O_{6}), or artificial murexide, which dies silk and wool a beautiful red colour On adding barium chloride to either of the above salts, a ver of barium iso-purpurate With aive a bright green precipitate Mr AH Allen gives the following methods for the assay of coanic analysis”:--