29 1. “On Nontroiiite,” by T. E. Thorpe Ph.D.* THEREexists some doubt among miiieralogists as to whether nontronite is to be regarded as a distinct mineral species. Owing to the difficulty of obtaining it in zy fit state for investi- gation the few analyses hitherto publisliecl by Berthier Du-frAnoy Jacquelin and others lmve taught us but little con-cerning its real nature. The followiug analysis made on a comparatively pure spec.imen may throw additional light on the constitution of this compound. The sample analysed was discovered unclassified in the mineralogical cabinet at Heidel- berg and was stated by Professor Blum who was disposed to regard it as pingnite t,o have been found in the neighbour- hood of Heppenheirn in the Bergstrasse. 1.4155 grm.of the substance was heatcd with filming hydro-chloric acid until the mineral appeared to be completely decom- posed ; the solution was evapordted to complete dryness and the separation of the silica effected in the usual manner. Silica obtained 0.5680 grm. The weighed silica was then dissolved in caustic potash and proved to be entirely free from said or quartz. To the filtrate from the silica were added a few drops of nitric acid the solution wa6 boiled and the iron precipitated by ammonia. Ferric oxide 0.5157 grm. The weighed precipitate was next dissolved in strong hydro- cliloric acid water added and the solution filtered from a iniriute quantity of silica which had escaped separation by the previous evaporation. Silica (not completely separated) 0*0030grm.* From the Pioceedings Lit. and Phil. Society of Manchester vol. ix No. 1 Sessiou 1869-70. VOL. XXIIL. D THORPE ON NONTROXITE. Catistic soda was then added in slight excess to the filtrate and the ferric oxide again precipitated waF;Eed ignited and weighed. The re-precipitated ferric oxide weighed 0.5740 grm. Hence the substance was free ii-orn any appreciable quantity of alumina. To the amnioniacal filtrate a few drops of ammonium oxalate were added and the precipitate was ignited and determined as caustic lime. Lime 0.0380 grm. On adding sodium phosphate to the filtrate a mere trace of magnesia appearing only after the lapse of some hours was found. The remaining constituent namely water was determined by igniting the mineral in a stream of dry carbonic acid carefully freed from air until the loss of weight appeared constant.1.1205 grm. substance lost 0.2311 grm. water. Calculated from the foregoing analysis the composition of the mineral is as follows :-Lime.. .............. 2.68 Magnesia ............ Traces Ferric oxide ......... 36-44 Silica.. .............. 40.30 Water .............. 20.98 -7 100.40 On subtracting the lime which evidentlymay be regarded as an unessential coiistituent the percentage composition agrees very well with that required by the formula- Fe20,3Si02 + 5H20. Found. Calculated. Ferric oxide. ..... 37-24 .... 37-20 Silica .......... 41-29 .... 41.86 Water .......... 21.47 ....20.94 100-00 lC0~00 Nontrouite ia evidently a product of the decomposition by THORPE ON A NEW CHROMIUM OXYCHLORIDE. weathering of some si!iceons mineral rich in iron. It poasesses a light green colour which on the expulsion of water changes to a dark chestnut brown. It is peifectly opaque and shows no evidence of crystallis~ttion. Its fracture is uneven and the lustre of its streak resinous. It is uiictuous to the touch yields easily to the nail and is somewhat harder than talc. The following analysis by Bietvend made upon a specimen found at Andreasberg agrees remarkably well with the fore-going determiiiat,ions :- Ferric oxide ..... 37.30 Silica.. .......... 41.10 Water .......... 21.56 99.96 2. ‘‘On a New Clironiium Oxychloride,” by T.E. Thorpe Ph.D.* prepared by heating a When chrom yl dichloride CrO, {:;y mixture of potassium dichroniate sodium chloride and sulphuric acid is maintailled at a temperature of 18Oo-19O0 in ill sealed tube for three or four hours it is almost completely converted into a black solid substance and on opening tlie tube when cold a consideraLle quantity of iiee cahlorine escapes. By ex-Iiansting the tubes containing the liyiiicl chloride before sub-jecting them to lieat I liave ascertained that chlorine is the only gaseous product of this decomposition. The black coinpomid inrariably contains more or less of the liqitid chloride which has escaped clecon?position the greater part of this is easily ex-pelled on gently heating the mam after opening the tube.In order to free it completely from the latter body the black substance was trailsferred to a clean tube and heated to 120” (i.e. about 2’ above tlie boiling point of cliroinyl dichloride) in a current of dry carboiiic acid gas until its weight appeared constant. The following cletermiiiation of the amount of chlorine coiitained in the volatile portion shows that it is simply chromyl clichlorid e which has remained undecompo sed. * Prom the Proceeding3 Lit. and Phil. Society of Manchester vol. ix No. 3 Session 1869-70. D2 0.8741 gram liquid chloride gave 1.6458 grams silver chloi-idt. Calculated for CrO_C12. Found. 45.7 per cent. 46.5 per cent. The solid snbstance dried in the manner above described appears as a black uncrpstalline powder which when exposed to the air rapidly deliquesces to a dark reddish brown syrupy liquid smelling of free chloriiie.When thyown into water it quickly dissolves forming a dark brown eolution which on standing also evolves chlorine. In the nitric acid solution hypo- chlorous acid appeare to be produced. In strong hydrochloric acid the substance dissolves with a dark brown colouration ;and 011 boiling the solution chlorine is evolved the liquid becomes greenish yellow and ultimately changes to the dark green colour peculiar to a solution of chromium sesquirxide in hydro- chloric acid. When it is thrown into dilute ammonia chromic acid is dissolved together with all the chlorine and a precipitate is formed possessiug the properties of the chromate of chrome sesquioxide (Cr,0,3Cr0,) dewxibed by St orer and Eliot.Upon this decomposition is based the method which I have employed for the estimation of the amount of chlorine contained in this body. The weighed quantity of the substance was treated with very dilute ammonia ; the solution boiled for a few miiiuteR and filtered ; the precipitate well washed by hot water ; an excess of nitric acid added to the filtrate; and the chlorine precipitated by the addition of silver nitrate. Two determina-tions of chlorine carried out in this manner on preparations made at different times gave the following results :-Preparation I. 0.5900 gram substance gave 0*4S70gram silver chloride and 0.0069 gram metallic silver.Preparation 11. 0.493 gram substance gave 0.4250 grain silver chloride. Prep. I ........ 20.80 per cent. C1. Prep. I1 ...... 21-32 , Mean ......... 21*06. In order to determine the amount of chromium it contains a weighed portion of the substance was repeatedly heated with CHROMIUN OXYCHLORIDE. strong hydrocliloric acid on a water-bath until the evolution of chlorine entirely ceased the solution was then diluted with water heated to boiling ammonia added in slight excess and the solution agdin boiled until the superiiatant liquid appeared perfectly coloui~less. The precipitated chrome sesquioxide was then filtered dried aid weighed. Preparation I. 0.3442 grm. substance gave 0.2470 grm. chrome sesquioxide. 0.5900 , , 0.4235 ,, 79 99 9 Preparation IT.0.5082 grm. snbstance gave 0.3590 grni. chrome sesquioxide. 0*5942 , , 0.4210 ,, 9 9 1 Prep. I 49.30 per cent. Cr. 49.23 , Prep. 11. 48-45 , 48.62 ,, -.-Mean .... 48.91 .. Hence the percentage composition of the substance is as follows :-Found. Ratios. Calculated. Chlorine.. .... 21-06 .... 2 .... 21.56 Chromium. .,. 48.91 .... 3 .... 48.54 Oxygen.. .... 30.03 .... 6 .... 29.60 attempted to control the above empirical formula by heating a weighed portion of the substance in The action of hydrogen upon the new chloride when heated is extremely energetic. At a comparatively low temperature it takes fire combustion proceeds rapidly through- out the mass and ultimately the substance is converted into chrome sesquioxide hydrochloric acid and water.Care must be taken to regulate the current of hydrogen since if it is too rapid particles of the finely-divided sesquioxide are apt to be mechanically carried away. From an experiment in which the gas was carefully purified from oxygeii by passing it through strongly alkaline pyrogallate solution and over heated metallic copper and then dried by traiismitting it through THORPE ON A NEW tiil-les containing pumice moistened with strong sulphuric acid the following numbers were obtained :-0.8715 grm. substance gave 0.6150 grm. chrome sesquioxide. Fouiid 7u.58 ps cent. Cr,O,. cr30,cl gives hy calcidation 70.72 ? I had an additional object in thus studying the action of hydrogen upon the new chloride.I considered that this action might possibly throw some light on the constitution of thia compound. The new oxychloride may in conformity with the analytical results be regarded as a compound of chromous chloride with two equivalents of chromium trioxide. Now chroinous chloride according to Moberg may be heated in hydrogen to the softening point of glass withoiit suffering de- composition ; and if it were found that water was the only volatile product of the reaction we should possess a certain amount of evidence for supposing that the formula CrC1,. 2Cr0 represents the coiistitution of this substance.. Esperiment showed however that the chlorine was not so firmly united in this compound as in the clirotnous chloride on gently heating the substance in hydrogen hydrochloric acid was immediately evolved.Pbligot has described a series of salts to which are assigned the general formulae &I C1 . CrO and Il”C1 .2CrO, where 11 represents a univalent. metal and M” a bivalent metal. The following are the names and formulae of the salts prepared by Pbligot :-K C1 ,CrO .... Potassium chlorochromate. Na Cl .CrO .. . . Sodium chlorochromate. NH4C1.CrO . .. Ammonium chlorochromate. Mg C1 . 2Cr0 . . Magnesium chlorochromate. Ca C1 .2Cr0 .. Calcium chlorochromate. Now the new oxychloricle stands in a very evident relation to these compounds. Supposing for a nioment that the formulae given to these substances correctly represent their constitut,ion then the new oxychloride may be regarded as the chromium term of the series-bivalent chrornium replacing magnesium or calcium.Cr”C1 . 2Cr0, a formula identical with that of which I have just attempted CHROil3;IUM OXYCHLORIDE. to sliow the impropriety. But there is still another reason for supposing that a compound thus constituted coiilcl not exist. Chrornous chloride is cbne of the most energetic deoxidisiiig agents known and we can hardly conceive it to be united in a stable compound with a substance which so readily parts with its oxygen as chromium trioxide. Hence I am disposed to regard the constitution of the salts of P6ligot as very different from that implied by the above method of representation indeed to the best of my knowledge the general formula assigned to these salts expresses not a single experimental fact unless it be the mode of their decomposition by water ; probably it had reference to the views of Ros e and Berzelius respecting the constitution of the so-called chlorochromic acid.The following structural formuh better represent in my opinion the constitution of these compounds and their relation to chromyl dichloride. Magnesium Chlorochromate. Chromium Chlorochromate. c1. c1. I I CrO CrO I 1 0 0 I Cr," I A 0 I I CrO GO I I c1. c1 These substances may also be thus represented :-cro2{f Cr02{F The relation of the new oxychloride to chromyl dichloride is thus very apparent. Three molecules of chromyl dichloride when heated are resolved iiito one molecule of chromium chlo- rochromate and four atoms of chlorine.