DR. GLADSTONE ON CBLOROPHOSPHURET OF NITROGEN. 135 XW.1.-On C~~oro~~os~~ure~ of Nitrogen and its Products of Decomposition. By J. H GLADSTOKE, PH.D. PART.I. A crystalline body containing phosphorus nitrogen and chlo- rine was discovered by Wiihler and Liebig during their investiga- tion of the compounds of nitrogen and phosphorus.* It was slightly examined by its discoverers and a partial analysis was made from which was deduced the probable formula P N Cl,. cc Chlorphos-phorstickstoff” was the name given to this substance which has been translated by Kan e :-<; Chlorophosphuret of nitrogen.” 1 am not aware that any chemist has since even prepared the body in question ;but I have lately submitted it to a complete investigation and shall now detail a portion of my results.In the paper upon the compounds of phosphorus and nitrogen which I had the honour to read before this Society last year,? chlorophosphuret of nitrogen was mentioned as invariably formed when pentachloride of phosphorus is saturated with ammoniacal gas. That its production does not depend upon any trace of moisture accompanying the ammonia I established by passing the gas through tubes five feet in length filled with sticks of potash when exactly the same result was obtained. I found it also produced when penta- chloride of phosphorus containing some terchloride was subjected to the action of ammoniacal gas; as also when the chloride was but imperfectly saturated with the gas. Thus it seems an invariable concomitant of the action of dry ammonia upon pentachloride of phosphorus.When the terchloride of phosphorus is saturated with ammoniacal gas no trace of this substance is produced. When thus prepared it is mixed with a large amount of chloride of ammonium and Gerhardt’s cc Chlorophosphamide.” In order to separate it from these the dry mass may be agitated with ether which dissolves out the chlorophosphuret of nitrogen leaving the other bodies. The ethereal solution will again yield crystals on evaporation; but as a secondary reaction is liable to take place be- tween the ether and the chlorophosphuret the following method of purification is to be preferred. The white mass resulting from the action of ammonia upon the pentachloride of phosphorus is placed in * Ann Ch,Pharm.XI. t Chem. SOC. Qu. J. 11,121. 136 DR. GLADSTONE a capacious retort half filled with water and the whole is brought into brisk ebullition ; the chlorophosphuret of nitrogen melts rises to the surface of the liquid is volatilized along with the vapour of water and condenses again in the neck in a state of purity. As it requires a long time to saturate the pentachloride of phos-phorus and as the amount of the crystalline body produced is very small proportionally this is a tedious process. Liebig found that the same could be effected by passing the vapour of pentachloride of phosphorus over chloride of ammonium heated almost to the point of sublimation in a glass tube three feet long in a coinbustion furnace. Impure phosphuret of ni trogeii is formed torrents of hydrochloric acid are given off and chlorophosphuret of nitrogen condenses in a receiver attached to the combustion tube.This is the process which I prefer ; but I have found it expedient to modify it in some degree. One part of pentachloride of phosphorus is mixed with 2 parts of well dried chloride of ammonit& in a Florence flask which may be half filled with the niixture. A series of two or more receivers is attached by means of tubes arid perforated corks. The first receiver should be dry and kept cool; the last should contain a considerable quan- tity of water. IIeat is then applied to thc flask either by means of a large flame of a spirit lamp or by glowing charcoal. The penta- chloride of phosphorus gradually sublimes combining with the chloride of ammonium which becomes red at first and is afterwards converted into a light brown substance wholly free from soluble chloride but retaining the original shape of the pieces.Chlorophos-phuret of nitrogen sublimes. In the first receiver condenses a limpid liquid with perhaps a small quantity of a white powder; whilst the hydrochloric acid gas is absorbed by the water in the last receiver and a little chlorophoephuret is also deposited there. When no more pentachloride of phosphorus remains undecomposed the flask may be suffered to cool and the chlorophosphuret of nitrogen contained in it may be separated from the other matters by either of the processes above detailed. The liquid condensed in the first receiver is colourless and fumes in the air emitting a pungent odour.When poured into water it does not mix but sinks to thc bottom; after the lapse of a minute or two violent chemical action ensues the liquid disappears chlorophos- phuret of nitrogen remains iii its place and the water holds in solu- tion hydrochloric aid phosphoric acids. No permanently elastic gas insoluble in water is evolved during this reaction. If the liquid under consideration be heated a large quantity of hydrochloric acid ON CHLOltOPHOSPHURET OF NITROGEX. is given off. A portion was taken and heated in a water-bath till the gas ceased to be evolved; the temperature was then raised and at 116O C. (240*8OF.) the liquid distilled over. When the thermo- meter began to rise rapidly the distillation was stopped and a liquid remained which deposited a quantity of crystalline chlorophosphuret of nitrogen on cooling.The distilled liquid was decomposed by water only a minute trace of the crystalline body was left; and the hydrochloric and phosphoric acids were precipitated in the ordinary way. 1.2025 grnis. of substance yielded 3.402 , , chloride of iilver and 0.870 ,) , phosphate of magnesia. These numbers reckoned to 100 parts are :-Phospho~s. . . . . 20*4~2 Chlorine . . . . . . 69.80 evidently indicating oxychloride of phosphorus P C1 0, which requires :* Phosphorus . 32.0 20.71 Chlorine . . 106.5 68.93 Oxygen . . 16.0 10.36 -I___ 155.5 100~00 The liquid in the first receiver-then is merely oxychloride of phos-phorus saturated with hydrochloric acid and holding in solution a variable quantity of chlorophosphuret of nitrogen.The formation of the oxychloride must be regarded as accidental. It arises from the access of air to the pentachloride of phosphorus during its preparation ; from the hygroscopic moisture which it is difficult to remove completely from the chloride of ammonium employed ; and perhaps also from the action of vapour of pentachloride of phos-phorus upon the cork. The amount of chlorophosphuret of nitrogen obtained by any of the processes just described bears but a very small proportion to the yentachloride of phosphorus employed-not more I believe than about; 6 per. cent. The quantity appears very uniform.* The slignt excess of chlorine arises in all probability from a small amount af lirdrochloric acid stjll retaincd by the liquid. 138 DlL GLADSTONE PROPERTIES OF CHLOROPHOSPHURET OF NITROGEN. Chlorophosphuret of nitrogen (at ordinary temperatures) is a solid crystalline body. It melts at about llOo C. (280° F.) into a clear liquid which enters into ebullition at about 240° (464O F.) When immersed however in boiling water it acquires a semi-fluid con- sistence; and I have observed that when liquefied and suffered to cool quietly the temperature will sink below looo C. without congelation taking place. Upon agitating it when in this statc the whole becomes a mass of crystals while the therniometer rises from evolution of latent heat.The form of the crystals as obtained by sublimation is that of a rhomboid of which the obtuse angle measures 131O or 132q the acute 48O or 49O the acute angle of this rhomboid either at one or both ends is often truncated when of course the angle formed is about 114O the hexagonal prism is also found. When crystallized from alcohol or from a mixture of alcohol and ether the same forms appear the hexagonal prism being conimon. By crystallization from ether I haye obtained it in the form of beautifully defined hexagonal pyramids the bases of which are in fact the truncated rhomboid before mentioned the angles being 1320 and 114O These pyramids are found attached base to base. The specific gravity of crystalline chlorophosphuret of nitrogen is somewhat greater than that of water but that of the fused compound is less.At ordinary temperatures the substance under consideration slowly evaporates; but when heated it diffuses a dense vapour having a somewhat agreeable but quite peculiar ociour. The taste of its solution in alcohol is of a bitter character. Chlorophosphuret of nitrogen is not soluble in water; indeed as observed by Liebig it shows great indisposition to be wetted by that liquid behaving in this respect like a fatty body. It is dis-solved by alcohol or chloroform and to a large extent by ether; it is likewise very soluble in bisulphide of carbon and in oil of tur-pentine benzol and other hydrocarbons. Its solubility in oxy-chloride of phosphorus has already been incidentally remarked.A decomposition which its solutions in. ether and alcohol spon-taneously undergo will be reserved for after consideration The original discoverers of this substance remarked that it is totally unaffected by aqueous solutions of either acids or alkalis and that fusion with hydrate of potash does not deconipose it. I find how-ever that if chlorophosphuret of nitrogen be brought in contact ON CHLOROPHOSPHURET OP NITROGEN. with such reagents through the medium of one of its solvents it is by no means so stable. Thus if it be treated with alcoholic solutions of potash soda or ammonia decomposition ensues and chloride with other salts of the alkali remain. Even some metallic salts when added to its solution in alcohol will give rise to a double decomposition ; thus if nitrate of silver be added an instantaneous formation of chloride of silver results.The crystals under consideration may be sublimed without altera- tion in an atmosphere of hydrogen or hydrosulphuric acid gas. When heated with iodine they are equally unaffected. Powerful oxidizing agents attack chlorophosphuret of nitrogen and give rise to the formation of phosphoric acid. Thus when its vapour is passed over chromate of lead or metallic oxides-for instance oxide of copper at a red heat-it is decomposed nitrous fumes being at the same time evolved. Nitric acid itself has no action upon the crystals unless it be fuming and at an elevated temperature yet if a solution in alcohol or oil of turpentine be employed the substance is much more readily attacked by the acid in quest ion.Metals themselves at a high temperature exert a decomposing in- fluence upon the vapour of chlorophosphuret of nitrogen a fact observed by Wohler and Liebig. Thus if it be heated in a tube in contact with metallic silver chloride of silver appears to be formed together with some salt equally insoluble in nitric acid and ammonia a little white sublimate is also formed which is soluble in water and con- tains chlorine. Again if a bright piece of silver be immersed in an ethereal solution of chlorophosphuret of nitrogen in a closed vessel it soon becomes coated with an incrustation of chloride of silver and the insoluble salt before-mentioned after the lapse of some weeks the decomposition will be complete and the ethereal solution will have acquired an acid reaction.Similarly if the substance in question be heated with potassium in an atmosphere of hydrogen gas combination ensues and chloride together with some other salt of potassium is formed And again if the crystals be dissolved in a pure hydrocarbon and pieces of potassium be added and heat applied combination takes place quietly. COMPOSITION OF CHLOROPHOSPHWRET OF NITROGEN. From the decompositions above stated it is evident that the crystalline body contains phosphorus nitrogen and chlorine. As 140 DR GLADSTONE it is produced without the piesence of air or moisture and as the pentachloride of phosphorus and the ammonia or chloride of ammo-nium from which it is formed are both free from oxygen it is sufficiently evident that that element cannot enter into the COM-position of the crystals.In order to satisfy myself as to the presence or absence of hydrogen in this compound I performed the following experiments. 1st. A weighed portion was burnt with chromate of lead and the water was collected as in the ordinary process of organic analysis metallic copper being placed in the anterior portion of the tube and extraordinary precautions being taken that every material employed should be perfect.1 y dry.-2nd. A long combustion-tube was filled with in the first place a weighed portion of the crys- talline body then several inches of copper turnings and reduced copper afterwards some chromate of lead separated €rom the former by a plug of asbestos and then again copper-turnings.To the combustion-tube was attached a srniall tube containing sticks of caustic potash and connected with it was one of Will's nitrogen apparatuses partially fillcd with dilute hydrochloric acid. Com-bustion was performed as usual. So small a trace of water or aiiinionia was obtained in either instance as to preclude the belief that hydrogen forms a constituent of the crystalline body submitted to experiment. The original investigators of this substance attempted an elementary analysis of it. The method adopted by them was that of decomposing the chlorophosphuret in a tube filled with uietallic iron. The gas given off was collected and estiniated as pure nitrogen; whilst the chloride of iron contained in the tube was vashed out and the chlorine precipitated as siher-salt.No attempt was made to estimate thc phosphorus. The results were NitroFen. . . . 11.2 10.1 979.2 per cent Chlorine . . . . 58.3 , > J From these numbers Wohler aud Liebig deduced the forinula P N Cl,; but knowing that the estimations of nitrogen were falla- cious they put it forward with little confidence thinking indeed that it might rather be P N Cl,. I employed various methods of decomposition for the analysis of this substance in order if possible to insure a correct result. I. 0.5225grm. of the crystalline body was dissolved in alcohol and a solution of nitrate of silver was added. Chloride of silver continued to subside for a couple of days.At length 1,246gri. was obtained. ON CHLOROPHOSPHURET OP 3ITROGEN. 11. 0.457 grm. vas decomposed by an alcoholic solution of am-monia. When evaporated to dryness and redissolved in water it yielded 1.0845grm. of chloride of silver. 111. 0*19412grm. was decomposed by an alcoholic solution of pure potash. This was evaporated to dryness and heated to redness in a tube along with fresh potash. The ammonia evolved mas collected in a hydrochloric acid apparatus and yielded 0-327 grm. of ylatinum- salt. The fused mass dissolved in dilute nitric acid yielded 0.4647 grm. of chloride of silver and 0.116 grm. of phosphoric acid estimated by nieans of bayyta. IV. 0.2655grm. was analyseci in the same manner as the preceding except that the fnsion with potash was conducted in a short silver tube inserted in an ordinary glass tube to which the hydrochloric acid apparatus was attached.It yielded 0.393 grni. of platinum-salt and 0.1552 grm.of phosphoric acid. V. 0.4375 grm. was boiled with fuming nitric acid in a vessel so contrived that the yolatilized chlorophosphuret of nitrogen was returned again to the oxidizing liquid. The phosphoric acid esti- mated by ineans of baryta-salt was found to be 0.2615 grni. VI. 0.2357 grm. was dissolved in alcohol and ether and boiled with nitric acid in a vessel similar to that employed in the last experiment. Violent action of course ensued and fresh alcohol and nitric acid were added until it was believed that the oxidation of the chloro- phosphuret was complete.The solution yielded 0.1593 grrn. of phosphoric acid. VII. 0.232 grm. was decomposed by passing it in vapour over red- hot oxide of copper. This method was found unsuitable for the de- termination of the chlorine as a part of it enters into some iiisoluble compound probably the dichloride. The mass remaining after the combustion was dissolved in hydrochloric acid ; and the phosphoric acid was precipitated from a very ammoniacal solution as the ain- monio-phosphate of magnesia. The portioii undissolved by hydro-chloric acid was then digested in strong nitric acid and the phosphoric acid thus fcrmed was precipitated as before. The second quantity of magnesia-salt being impure was again fused with carbonate of potash and the phosphoric acid reprecipitated.The whole amount of pyrophosphate of magnesia obtained was 0.2605 grm. These results reckoned to 100 parts are :-J. 11. 111. IV. v. VI. VII. Phosphorus -7 26.52 25-99 26.55 30.08 31.69 I Nitrogen -10.55 9.19 ---c Chlorine . 58.83 58.53 59-02 -- 1 42 DR GLADSTONE This confirms the formula of the discoverers P N Cl, which would require :-a Phosphorus 96.0 31.84 Xitrogen . . 28.0 9-29 Chlorine . 177.5 58.87 301.5 10OwO0 The majority of my determinations of phosphorus it will be seen indicate an amount considerably below that required by theory ; yet I think this presents no great obstacle. The compounds contain- ing phosphorus and nitrogcn into which the chlorophosphuret of nitrogen is resolved are themselves very difficult of decomposition some unrecorded experiments conducted by other methods yielded estimations of phosphorus which were much smaller and unques- tionably incorrect.Froin the amount of nitrogen and chlorine obtained it is manifest that if the crystals contain no other element than phosphorus beside these such an amount as 26 or 27 per cent requires the addition of 4 or 5 to complete the 100 parts (vide Experiment 111 in which the sum of the three numbers is only 96.09). The 7th experiment does give a result coincident with theory ; yet unfortunately from the difficulties attending it I cannot lay much stress upon this determination. The method adopted in the 6th experiment is I conceive worthy of the greatest reliance and that yields 30.08 per cent of phosphorus.Besides which an indirect method of analysis which will be detailed towards the close of this paper afforded a determination of the amount of phosphorus equal to that required by the formula P N (21,. AZOPHOSPHORIC ACID Ii.on-saZt.-It bas already been remarked that if chlorosulphuret of nitrogen be dissolved in alcohol and potash or ammonia be added decomposition instantly ensues. Now if this solution be evaporated to dryness redissolved in water and rendered perfectly neutral it gives no precipitate on the addition of most inetallic salts thus proving that it contains no phosphoric acid. If however the neutral solution or the solutioii rendered strongly acid be boiled with a salt of sesquioxide of iron a white flocculent precipitate speedily forms.It has the appearance of the ordinary phosphate of the sesquioxide of iron but it is at once distinguishcd from that salt by the two remarliable properties of being insoluble in dilute acids but completely solitble in ammonia. When treated with a solution of ON CHLOROPHOSPHURET OF NITROGEX. potash this salt is immediately decomposed ; sesquioxide of iron remains; and in solution is a potash-salt of the new acid from which the iron-salt may again be formed by neutralization with acid and the addition of any solution of that metal. Alkaline carbonates decompose it upon the application of heat. If it be fused with potash ammonia is evolved; and the fused mass redissolved in acid and treated with ammonia gives ordinary phosphate of iron.Strong sulphuric acid clissolves it and decomposes it when warmed. The action of heat upon this salt is remarkable. When dried at ordi- aary temperatures or at loooC. it has a white or rather a light buff colour ;but when heated to aboat 330° C. (572OF.) it suddenly gives off vapour of water and ammoniacal gas assuming a dark brown colour while a small quantity of a white crystalline body also sublimes. This sublimate is soluble in water; when it is treated with a solution of nitrate of silver a white precipitate is produced which changes immediately to a clear orange-red; and shortly afterwards there is formed a quantity of black substance insoluble in ammonia ap- parently reduced silver. The iron-salt gives off water preparatory to decomposition even when previously dried at 220° C.(428OF.) Although this salt does not present itself in crystals the fact of its being formed in decidedly acid solutions is a tolerable guarantee of its purity. I have prepared it at as low a temperature as 46O C. (114*8*F.),but a higher degree of heat is desirable so as to ensure a complete transformation Analyses were effected by the following methods. I. 0.2735 gym. of salt dried at 1000 C. was fused with pure hydrate of potash in the short silver tube mentioned above inserted within a glass tube. The evolved gas was collected in Will’s hydro- chloric acid apparatus and yielded 0.248 grm. of ammonio-chloride of platinum. The fused mass was then dissolved in water filtered and the phosphoric acid in the solution was precipitated as magnesia- salt.The undissolved oxide was fused with a mixture of the carbon- ates of potash and soda to separate aiiy phosphoric acid which niight still be combined with it following the directions given by Rose in his paper 011 the estimation of phosphoric acid in Pogg. Ann. Part 11. for last year. The amount of sesquioxide of iron obtained was 0.0943 grm. The additional pyrophosphate of magnesia obtained was 0.005 grm. to be added to the previous amount 0.2373 grm. 11. 0,215 grm of salt dried at 70° C. (158O F.) weighed only 0.205 grin. when dried at 120°C. (248O F.) This was decomposed per se by heat in a glass tube to which was attached a tube contain- ing sticks of caustic potash.The loss of weight during thc process of heating was 0.0405 grm. ; the amount of water collected was 0.0145 grm. The mass remaining in the tube was fused with caustic potash; and the ammonia evolved collected in a hydrochloric acid apparatus yielded 0.0215 grm. of platinum-salt. As the substance had been fused with potash in a glass tube it was very probable that some other oxides beside sesquioxide of iron existed in the alkaline mass for this reason the method suggested by Rose foi* the separation of mixed oxides from phosphoric acid by means of nitric acid and mercury was adopted. The amount of sesquioxide of iron was found to be 0.0695 grm; that of pyrophosphate of magnesia obtained was 0.179 grm. 111. A portion of iron-salt which had been allowed to remain seven days in vacuo over sulphuric acid weighed O%A grm ; when dried at between I 20° and 130°C.(248°-2660 F.) it parted with moisture and weighed only 0.2422 grill. The salt heated as in the preceding experiment lost 0*0475grm. The amount of water col- lected in the tube filled v-ith sticks of potash was 0.0.29 grm; the arnnioniacal gas given off and collected in a hydrochloric acid apparatus annexed to the tube for absorbing the moist ure yielded 0.110 grm. of platinum-salt. The remaining mass was fused in the silver tube and evolved gas which afforded 0.022 grm. of pure chloride of ammonium. The amoxiiit of sesquioxide of iron in the alkaline mass was 0.0835 grm IV. 0.2112 gmi. of iron-salt dried at a temperature of 1600 C (320°F.) heated as in preceding experiments showed a loss of 0,0393 grni.The amount of water collected was 0.025 grm. ; that of platinum-salt was 0.0755 grm. The salt was fused with potash as before but the amount of ammonia evolved was not correctly as- certained. The resulting mass was dissolved in acid; arid since I had learnt by experience that the entire amount of phosphoric acid pro-dixced by the decomposition of such substaiices as these phosphorus compounds is seldom if ever precipitated by magnesia-salt the sepa- ration of the sesquioxide of iron from the phosphoric acid was effected as in the preceding cases but the acid itself was estimated by means of baryta. The amount of sesquioxide of iron was 0.071 grni.; that of phosphoric acid 0.133 grm.It will be evident froin consideration of Experiments 111. and IV. that some other gas besides ammonia and vapour of water is evolved when this iron-salt is heated Thus Rater. Ammonia. Actual loss. Exp. 111. 0.0229+ 0*0084= 0.0374 not 0.0475 asp. ITr 0.025 + 0.0057 = 0.0307 , 0.0393 O’J CHLOROPHOSPHUEET OF NITROGEX. If we suppose that the animouia did not exist a3 such in the iron-salt which is of itself improbable but that it was formed under the influence of heat by the combination of nitrogen with hydrogen which was itself obtained from the decomposition of a portion of the water; and that the oxygen thus set free was evolved along with the other gases ve have a theoretical loss coinciding very nearly with that actually found.Decomposed Theoretical Actual Rater. Nitrogen. water. loss. loss. Exp. 111. 0.029 +0.0069 -j-0.0015 x 9 =0.0494 0*0475 Exp. IV. @026 +0.0047+0*0010x 9 =0 0387 0.0393 If we calculate the ammonia evolved in the secoiid experiment on the same principles as this we have assuming x as the amount of hydrogen in the water that wasdecomposed 14X 0.0145f-+9 x =0*0406, 3 from which it appears that the quantity of hydrogen combined to form ammonia was 0.0019 grm. ;and the nitrogen with which it united itself must have been O*OO9 grms. The percentage amount of the elements reckoned from the numbers obtained in the four experiments recorded above is subjoined. The weight of iron-salt as dried at a temperature not lower than looo C.is assumed as the basis of the calculation; and I have also added in brackets the amount of hydrogen and nitrogen in the second experiment as estimated on theoretical grounds from the loss. I. 11. nr. iv. Sescpioxide of iron 34.48 33.90 34-47 33.62 Phosphorus . 25.05 25.07 -27.93 Nitrogeii ... 5.67 C5.071 5-24 -Hydrogen ... -[1-70] 194 1.81 These numbers accord sufiicientl ywith those deduced from the formula Fe,O,. P,NO,. 4FiO. Sesquioxide of irou ....80 34-19 Phosphorus . . .64 27.35 Nitrogen ....... It 593 Hydrogen ....... 4 1.71 Oxygen ........72 30.77 -234 1oo*oo VOL. 111.-NO. x. L I4!6 DR. GLADSTONE If we assume as the basis of our calculation the weight of iron-sal as dried at 70°C. or at ordinary temperatures in vacuo and add the amount of water driven off at a higher degree of heat we have for the second and third experiments I.11. Sesquioxide of iron . . 32.33 32.87 Phosphorus . . . . . 23.92 __. Nitrogen . . [4.83] 5.00 Hydrogen . . . . t2.131 2-36 corresponding with the numbers deduced from the formula Fe 0,. P IS0,.5 HO Sesquioxide of iron . . . . 80 32.92 Phosphorus . . . . 64 26.34 14 5.76 Xitrogen . * . . 5 2.06 Hydrogen . . . . . . . . . . . 80 32.92 Oxygen. -243 loonoo In what light these 5 atoms of water are to be viewed I know not I have in vain sought the aid of powerful microscopes for any crystalline appearance in the precipitate. It seems also that one of the atoms must be regarded in a different manner from the four others since it is driven off at the boiling-point of tvitei; while the rest remain COMPOUND OF THE IRON-SALT VITH A;C.fNONIA~ It has already been stated that the iron-salt is entirely soluble in ammonia.It gives a red solution from which the iron-salt may be again precipitated by the addition of an acid. An attempt was made to obtain this compound salt in the dry state. An ammoniacal solution was carefully evaporated in a water-bath it came out as a dark red mass very soluble in water but manifesting no disposition to crystallize. After being perfectly dried it was treated with water when it separated into two portions; the one soluble containing ammonia and giving a characteristic precipitate when treated with acid; the other like micaceous plates of the colour of red prussiate of potash which appeared to be mainly sesquioxide of iron.Similar salts of other oxides may be produced from the chlorophos- phurct of nitrogen in the same manner as the iron-salt just described ; bnt that is the only one as far as I have observed which tvill preci- ON CHLOROPWOSPHURET OF NITROGEN. pitate from very acid solutions. Hence it is the salt upon the purity of which the greatest reliance can be placed and I accordingly chose it for the most particular examination. Alumina-salt.-This is prepared when a solution of alum is added to an aqueous solution of chlorophosphuret of nitrogen decomposed by ammonia and alcohol which should be slightly acid to test-paper.No precipitate falls in the cold but upon boiling the mixture a white flocculent precipitate is formed. This is an alumina-salt similar to the iron-salt already investigated when dry it is pulverulent upon being heated in a test tube it becomes black then again white giving off ammonia water and a small quantity of the white sub- limate mentioned as being also formed during the destruction of the iron-salt. C~pper-saZt.-When sulphate of copper is added to the same slightly acid solution of chlorophosphuret of nitrogen and the mixture boiled a pale blue flocculent copper-salt precipitates. When heated per se this salt fuses smells up becomes black and afterwards lighter in colour and evolves ammonia vapour of water and the same white sublimate.It is wholly decomposed by a cold solution of potash. An analysis was made. 0,2923 grm of copper-salt dried at lOO*C. was heated in the same manner as the iron-salt. The loss in weight was 0-0468 grm.; the amount of water collected was 003.0 grm. ; that of platinum-salt obtained was 0-0172 grm. The remaining mass was then fused with potash. The amount of pure chloride of ammonium obtained from the evolved gas was 0.011 grm. The oxide of copper was separated from the phosphoric acid by fusion with alkaline carbonates with the pre- cautions recommended by Rose in the memoir already more than once referred to. It weighed 0.124grin. These iiumbers reckoned to 100 parts accord sufficiently with the formula 3 CuO. P NO,.5 HO. Calculated. Found. Oxide of copper . 119 42.20 42-42 Phosphorus . . . 64 22.70 -Nitrogen . . . 14 4.96 4.72 Hydrogen . . . 5 1-77 1.94 80 28.37 -Oxygen * 282 100.00 From the amount of water and ammonia evolved during the heating of this copper-salt compared with the actual loss of weight it 22 mould appear that uiilike the iron-salt a portion of the oxygen set free by the deconiposition of water was not given off along with the other gases. Decomposed Theoretical Actual Water. Nitrogen. water. loss. loss. 0.030 + 0.0108 -i-0*0024x 9 = 0-06.24 instead of 0.0468 Since the heated ixiass after becoming black became again white it seems probable that the phosphuret of the metal or some such compound-to which without doubt the black colour in these de- compositions is owing-was oxidized by the free oxygen ; and this will account for the decrease of weight being less than that expected.SiZz;er-salt.-If to a neutral solution in water of the salts obtained by the decomposition of chlorophosphuret of nitrogen by means of alcohol and ammonia excess of nitrate of silver be added a dense precipitate falls consisting principally of chloride of silver. If this be shaken and removed by filtration and the solution be boiled a bulky white precipitate forms. This salt wlien collected and dried has the appearance of a granular grey powder little affected by light. When heated per se it fuses swells up greatly and evolves the usual gases becoming at the same time black which is aftern-arch exchanged for a greenish colour.A quantity was prepared for analysis by a different process. Some of the iron-salt \+-asdecomposed by a solutiorr of potash in the coId; the resulting solution was neutralized by nitric acid and nitrate of silver was added. Thc salt thus obtained wts analysed in a similar manner to the preceding. It was dried at 160° C. (328O I?,} but it appeared to lose nothing between 8Uo C. (1'76O F.) and that point when it began to soften. I. 0,1385 grni heated pw se showed a loss in weight of 0.005 grm. The amount of water collectccl was 0.0018 grill.; that of platinum-salt obtained was 0.0225grm. After fusion n ith ptash the amount of platinurn-salt obtainect was 0.025 grm. The alkaline mass dissolved in dilute nitric acid and treated with hydrochloric acid gave 0*1075grm.of chloride of silver ; and the phosphoric acid estimated by means of baryta-salt was 0.0499 grm. 11. 0.394 grm. of a separate preparation decomposed by dilute hydrochloric acid yielded 0.333 grin. of chloride of silver. These numbers reckoned to 100 parts yield I. 11. Oxide of silver . G7-15 68.39 Phosphorus . . 13-79 -Nitrogen . . . 2.17 -IIydrogell . . . 0.36 7 ON CHLOROPHOSPHURET OF NITROGEXe Prom the amount of base it would appear that the silver-salt is strictly analogous in composition to the copper-salt just described ; and yet the amount of hydrogen obtaiiied would rather indicate 2 atoms of water than 5. It must however be borne in mind when estimating the value of these analytical results that the varying quantity of white sublimate may always introduce an error more or less great in the determination of hydrogen.Calculation from the formula 3 Ago. P NO,. 5 HO Oxide of silver . . . 348.9 68.16 Phosphorus . . . 64 12.50 Xitrogen . . . . . Hydrogen. . . . . 11 5 2.73 0.98 Oxygen . . . . . 80 15.63 5119 100*00 The comparison between the actual loss of weight in the first expe- riment and that calculated from the amount of water and ammonia found reckoning the whole oxygen to be evolved is as follows :-Decomposed Theoretical Actual Rater. Nitrogen. nater. loss. loss. 0*0018+ 0.0014 + 0.0003 x 9 = 0.0059 0.005 Lead-salt.-The lead-salt may be prepared by siniilar methods.It is white and granular when dry. If decomposed by heat it coin-ports itself in the same manner as the salts previously described. It is decomposed not dissolved by ammonia. Mercury-salt.-Flocculent mercurial salts may be prepared from the potash-salt by double decomposition with either the subnitrate or protonitrate of mercury. That containing the suboxide is white with a slight tinge of yellow. When heated per se after being dried in vacuo it becomes black water and ammonia and the white subli- mate are given off; the mass fuses and swells greatly and metallic mercury eventually sublimes. Raryta-salt.-This salt cannot be obtained in the pure state by adding a solution of n haryta-salt to a neutral or slightly acid solu- tion of decomposed chlorophosphnret of nitrogen.It may however be easily prepare$ when the iron-salt is decomposed by a cold solution of potash the resulting liquid neutralized by acid and nitrate of baryta or chloride of barium added. The salt thus obtained is white and flocculent when dried and heated per se it gives off the same bodies as all the other salts of this acid which 1 have examined becoming in the meantime of a dark brown colour. 150 D11. GLADSTOSE The analysis was effected in the usual way. I. 0.2195 grni. of baryta-salt precipitated from a slightly acid solution and dried at 150° C. (302OF.) showed a loss of weight upon heating of 0.0135 grm. The water collected was 0 0045 grm. ; the platinum-salt obtained 0.069 grm. After fusion with potash the platinum-salt obtained was 0.020grm.The sulphate of baryta pre- cipitated was 0.224grrn. and the pyrophosphate of magnesia pro- duced was 0.137 grm 11. 0.1487 grm. of baryta-salt precipitated from a solution ren-dered slightly ammoniacal and dried at 150° C. showed a loss of weight upon heating of 0 0092 grm. The water collected mas 0.005 grm.; the platinum-salt obtained 0.029 grm. After fusion with potash the platinum-salt obtained was 0.033 grm. The sulphate of baryta precipitated was 0.1415 grm. and the pyrophosphate of magnesia produced was 0.0815 grm. These numbers reckoned to 100 parts accord best with the per- centage deduced from the formula 3 BaO. P NO,. 2 "0. Calculated. Found. I. I1 t Baryta . . . 230 62*84 66.92 62.45 Phosphorus 64 17.49 17.63 15.47 Nitrogeiz .. 14 3.82 2-55 2.62 Hydrogen . 2 0.55 0.64 0.63 Oxygen .. 56 15.30 -366 100*00 The salt analysed in the first experiment appears to have been impure. The actual loss of weight upon heating the salt in each of these experiments is a little less than that calculated from the amount of water and ammonia collected supposing the whole of the oxygen set free to be given off as such. This must be ascribed to the same reason as in the case of the copper-salt. Decomposed Theoretical Actual Water. Xtrogen. water. loss. loss. Oflo45 + 0.0043 + 0*0009 x 9 = 0,0169 instead of 0.0135 0*0040+ 0.0018 + 0.00089 x 9 = 0.0103 , ,)0.0092 In glancing over these analyses it will be remarked that the amount of nitrogen obtained is in every instance below that required by theory and in some cases the deficiency is very considerable.I believe this is solely due to the nitrogen not being entirely converted ON CNLOROPHOSPHURET OP NITROGEN. into ammonia during the fusion with potash and to the difficulty of collecting the whole quantity of gas then evolved. This opinion is supported by the fact that in the copper-salt where the large amount of water permitted the nitrogen to be mostly given off as ammonia when the salt was heated per se the amount of nitrogen found very nearly equals that calculated from the formula ; while in the baryta-salt where the very small amount of water precluded mucn of the nitrogen being thus given off the deficiency was far more considerable.I have also prepared by similar methods compounds of this acid with the oxides of chromium manganese nickel cobalt zinc cad- mium and tin besides strontia lime and magnesia. A11 these present themselves as flocculent precipitates; and all are of a white colour except the cobalt-salt which is pink. No precipitate is ob- tained iipon mixing a solution of the potash-salt with either a solu-tion of bitartrate of antimony and potash or a solution of terchloride of gold. If the iron-salt be decomposed by soda and the alkaline salt thus obtained be rendered slightly acid and a solution of bichloride of platinum be added no precipitatc results. I obtained however a compound containing this metal when a mixture of the bichloride and potash-salt was evaporated to dryness.It wasof a brown colour insoluble in water and soluble with difficulty in hydrochloric acid when heated in a tube it assumed a swimming appearance from the escape of gas; water was given off together with a little white sublimate and-not ammonia-but hydrochloric acid in considerable quantity. The substance in the tube became quite black and after- wards brown like spongy platinum. It is possible that this COM-pound may contain potash. Potash-salt.-The compounds of this acid with the alkalis being soluble in watcr cannot of course be obtained in a fit state for analysis in the same manner as the metallic salts. In order to obtain a pure potash-salt some of the iron-compound was decomposed by means of a quantity of the purest potash not equivalent to thp whole of the iron.The solution was neutral to test-paper whilst a portion of the white salt unconverted into the red oxide of iron was a further guarantee that the whole of the caustic alkali had entered into a new compound The filtered solution was evaporated in vacuo over sulphuric acid. It was hoped that a crystalline salt would thus be obtained but it dried to a greenish gum-like mass deliquescent in moist air but insoluble in alcohol. It was analysed by the addition 152 DR. GLADSTONE of bichloride of platinum and free hydrochloric acid; but owing to the formation of the peculiar platinum-salt noticed above it is doubtful whether the whole of the alkali was converted into the double chloride of platinum and potassium.Yet from 0,1243grni. of the salt dried in vacua thcre was obtained 0.272 grm. of double chloride which is equivalent to Potash-42.35 per cent. Now the conipositioii 3 KO. PzNO,. 5 HO would requirc Potash-46-49 per cent a quantity not much larger. Ammonia-salt.-When the lead-salt is decomposed by dilute am.. monia and the solution thus obtained is evaporated in uacuo over sulphuric acid the ammonia-salt presents itself as a viscid mass without showing the slightest tendency to crystallize. It is very soluble both in water and in alcohol. Free acid.-My first attempts to obtain this acid in the free state were made by deconiposing the copper-salt diffused through water by nieans of a stream of hydrosulphuric acid ;but a breaking- up of the liberated acid into siiupler forms seemed always to ensue at least after the lapse of a short time it was resolved under the influence of water into compounds of ammonia with phosphoric or phosphorous acid.But on treating the silver-salt with dilute hydro- chloric acid a solution was obtained from which the characteristic iron-salt could be readily produced. This mas evaporated down at first by heat afterwards under the air-pump. Some crystals ap- peared which however swelled and broke up before the mass became perfectly dry. A semi-solid non-crystalline substance remained which proved to be the acid in question. The acid thus obtained is deliquescent in moist air readily soluble in water or alcohol and slightly so in ether its solution reddens blue litmus-paper and has an agreeable acid flavour.It may be subjected to a high degree of heat without alteration; but if heated on platinum-foil iu the flame of a spirit-lzmp it fuses blackens and eventually rises in vapour. The salts already described may be prepared from it :thcs if it be treated with ammonia in excess and a minute quantity of a solution of sulphate of sesquioxide of iron be added not the slightest trace of sesquioxide appears but the liquid assumes a clear red colour. This I esteem the most characteristic single test of the acid in question. It appears then that me have here a peculiar acid resembling phos- ON CHLOROPHOSPHURET OF NITROGEN phoric acid both in its terbasic character and in the general physical and chemical character of its salts but differing from phosphoric acid in constitution since it contains one atom of phosphorus and one atom of nitrogen in addition to PO,.Without reference to any particular theory I shall simply denominate it Azophosphoric acid. A list of the salts analysed is annexed in the subjoined table for the purpose of comparison. Salt. Dried at Composition. Azophosphate of iron . below 100° C. Fe 0,. P,NO,. 5 HO 9 >> 100°-1600 C. Fe 0,.P NO,. 4 HO , of copper . 1000 c. 3CuO. Y NO,. 6 HO , of silver . 1000-16O0 C. 3AgO. P NO;. 5 HO , of baryta . 150°C. 3 BaO. P,NO,. 2 130 , of potash Ord.teni. invac 3 KO. P,N05.5 HO? It occurred to me that the readiness with which the azophosphate of iron is produced from the chlorophosphuret of nitrogen might be taken advantage of in the analysis of that substance particularly in reference to the amount of phosphorus.A weighed portion of the crystals was therefore dissolved in alcohol decomposed by ammonia evaporated to dryness and the resulting mass re-dissolved in water. An acid solution of sulphate of sesquioxide of iron was then added and boiling was continued for an hour. The salt thus precipitated was collected on a weighed filter and dried at 100°C The filtered solution was evaporated to dryness treated with a. little hydrate of potash re-dissolved in acid and precipitated by ammonia. The mixture of phosphate and oxide of iron thus obtained was analysed by fusion. 0.2803 grni.of chlorophosphuret of nitrogen yielded 0*180 , , azophosphate of iron and 0.1435 , , pyrophosphate of magnesia. Assuming that phosphorus constitutes 27.35 per cent. of azophos-phate of iron these results indicate Phosphorus-32-00 per cent an estimation equalling or rather just exceeding that required by the formula P N C1; viz. Phosphorus-31*84 per cent. In the present paper I have confined myself to a mere description and analysis of this crystalline body the so-called ‘I Chlorophos- 154 MI%. WILSON phuret of Nitrogen,’’ P N C16;and of a peculiar acid with its salts 4‘ Azophosphoric Acid,” P NO,. Upon the manner of formation of the first cotnpound and upon the reactions by which the second is derived from it I hope to cnter at some future opportunity when I anticipate laying before the Society some further products of the decomposition of chlorophosphuret of nitrogen and among them some which will probably facilitate our understanding of the ratioual com-position of the bodies here described.