CHURCH ON SOME HYDRATED CUPEIC OXYCHLORIDES. 77 XV.-On. some Hydrated Cupric Oxychiorides from Cornwall. By A. H. CHURCH,MA. Professor of Chemistry B.A. College Cirencester. 1 HAVE lately received from Cornwall a copper mineral which proves to be new. Qualitative analysis of the specimen shewed it to con-tain chlorine copper and the elements of water ; very precise test- ings subsequently revealed the presence of traces of carbonic acid arsenic aluminium and sodium ;but these substances exist in most minute proportion in a carefully selected sample-indeed their quantity is too insignificant to admit of estimation. CHURCH ON SOME HYDRATED The colour of the new mineral is bright blue slightly inclining to green (turquoise-blue) ; it occurs in thin crusts consisting of irregular aggregations of minute globules which present a botry-oidal appearance under the microscope.The globules are dis- tinctly subcrystalline and subtranslucent. The hardness of the mineral approaches 3 ;its density has not been determined with exactness but it is about 3.5. The streak of the new mineral is white; it is extremely fragile. It is insoluble in water but quite easily soluble without residue even in dilute acids and in ammonia. It is hygroscopic when kept in dry air it loses some hygroscopic water without change of colour but it rapidly becomes green at loo" acquiring a tint similar to that of atacamite this change of colour is accompanied by a further and considerable loss of water. On ignition the cupric chloride volatilizes in part ;the final residue is of a dark olive-green tint.Fm analysis the mineral was dried in vucuo over oil of vitriol until it ceased to lose weight 3 the sample had been most care-fully selected in order that the results of the analysis might be completely free from the disturbing inflfience due to any impuri- ties ; for under the microscope it was seen that the botryoidal or pisolitic crusts although constituting the hulk of the mineral were accorripariied by traces of foreign salts. These salts were calcic sulphate," ferric oxide &c.; the latter oxide being also the matrix of the mineral. The following are the analytical details :-I.-1.185 grammes lost in vacuo -055 gramme water. II.-1.13 grammes gave *505gramme chloride of silver.111.-598gramme gave *251gramrue chloride of silver. IV.-1.13 grammes gave .718gramme cupric oxide. V.-*752gramme gave ,499 gramme cupric oxide. V1.-405 gramme gave -268gramme cupric oxide. A third determination of chlorine mas made in another sample which was less piire containing compouiids of cslciiim arid iron in more than mere traces. Not haviug the requisite data for cor-recting the result I have omitted it relying upon the numbers above given the accuracy of which I have no reason to doubt. The greater part of the single specimen of' the new mineral mas * A eomplete analysis of Connellite a cupric aulphato-chloride (from Corn-lvall) is greatly to be desired. In the outer blue layer or crust of our mineral itself a trace of snlphuric acid was found but 212 rnilligrammes gave 2 milli-grammes only of barium-sulphate.CUPRIC OXYCHLORIDES FROM CORNWALL. consumed in these analyses for some of which I took as will be noticed an unusually large amount of substance in order to lessen the effect of any errors of manipulation.* Translated into percentages the experimental results are as follow :-I. Hygroscopic water lost in vacuo .. 4.64 p.c. 11. Chlorine . . .. .. .. 11.05 p.c. 111. Chlorine .. .. .. IV. Cupric oxide . .. V. Cupricoxide .. .a VI. Cupric oxide .. .. To what formula do these percentages correspond? There is but one native hydrated cupric oxychloride-atacnmite but it contains more chlorine than $he salt now under review.Ata-camite Seems often to have the composition expressed by the formula :-CuC1 3CuH202.aq. ; sometimes it has a smaller percentage of water sometimes it is more highly hydrated. The formula which furnishes proportions most nearly approaching to the blue oxychloride is- as the following comparison of the theoretica4 and experimental percentages will shew :-Theory. Experiment. CuCl,. 4CuH202. 4ag. mean. ZC1 .... 71-0 .. 11-91 or 11'91 11.33 cu.., 63$ .. '*"' 1 66.6OCuO 66.24 4CuO .. 318.0 .. 53-29 8H20 .. 1440 .. 24.16 24-16 --3 596.5 100°OO 102.67 The new mixiera€ thus differs chemically from the allied species atacamite in a most urnistakeable manner. Not only is it more highly hydrated but it contains the cup& cliloride and cupric hydrate in different proportions.f A special determination of impurities zinc-oxide &c. was made in one instance ;they amounted to -75 per cent. on the vacuum-dried mineral. 80 CHURCH ON SOME HYDRATED CuC1 CuH,O Atacamite 1 3 New species 1 4 The physical characters of the two minerals are also as I have already remarked very distinct. A few words as to the water in the mineral may not be out of place here. Crystallized cupric chloride is green and has the formula CuCl2.2aq. When this salt is dissolved in some quantity of water it becomes blue; just 30 the less hydrated mineral atacamite is green; the more hydrated new species is blue. So also with the blue langite and pale blue lyellite as compared with the green brochantite.Atacamite.. ,. CuCl . 3CUH,02 aq. green. New species.. CuCl . 4CuH,02 . 4 aq. blue. Brochantite .. 2Cu80 . 5CuH,O green. Lan@te* .... CuSO; . 3CuH,O,. aq. blzle. Lyellite. ..... .3Cu,H,02 . 3 aq. blue. The following details concerning the atacamite recently de- tected in Cornwall are given in part for the sake of comparison. These are the results on analysing an extremely pure spe-cimen :-1. 11.24 grains lost 27 grains in vacuo. XI. 11-98 grains lost 2.05 grains at 270°C. 111. 11-24grains gave 6.07 grains AgC1. IV. 12.8 grains gave 7-1 grains AgCl. V. 11.24graius gave 7-85 grains CriO. VI 11-33grains gave 7.89 grains CuO. The formula CuCl . CuH,O .aq. demands the following per- centages :-2Cl .... 71.0 15-97 or 15.97 cu .. .. (33.5 '''%171-43 Ct10 3CuO -. 238.5 53.58 4H,O .. .. 72.0 16.19 16.19 445.0 LOOoOO 103.59 These are the percentages deduced from the foregoing analyses of atacamite :-* Or for the sake of more ready comparison with brochantite langite may be represented thus 2CnS0,.6CuH2O2.2aq. CUPRIC OXYCHLORIDES FROM CORNWALL. Hygroscopic water lost in vacuo . . I. 2.40 P.C. H20 lost at 26OoC .. .. 11. 17.11 p.c. or c1 .. 111. 13-35 p.c. c1 .. .. IV. 13.70 p.c. CUO .. .. V. 69.84 p.c. CUO .. .. VI. 69-34! p.c. Analysis 11. does not represent the percentage of water in atacamite accurately It was observed that this mineral does not lose water alone when heated in the oil-bath to 260' C. Hydro-chloric acid is also evolved while a part of the water is yet obstinately retained even at the temperature at which cupric chloride begins to be given off.The numbers deduced from Analyses 111.to VI. require a correction to be made in them for hygroscopic water (see Anal. 1.j before they can be compared with the theoretical percentages :-Experiment.(Nean corrected p.c ) Theory.(CuC1,.3CuH20:.aq.) c1 0. .. 15'20 15.97 CUO .. .. 71.31 71-43 H20 .. .. - 16.19 103*59* The deficiency in the experimental and calculated chlorine and cupric oxide is most probably due to the hygroscopic water not having been absolutely removed by desiccation in vacuo over oil of vitriol ; its influence has consequently been under estimated. The proposed formula agrees more nearly with the results of analysis than the expressions usually adopted for the several varieties of atacamite :-CuC1,.3C uH ,Q CuC1,.3CuH20,.l~aq.CuCl2.3CuH,Q,.2aq. CuC1,.3CuH20,.3aq In all these formulse however the proportion of cupric chloride to hydrate is maintaiiied constant. It is worthy of note that not only have several varieties of atacamite been prepared artificially but that a compound corresponding to the salt described in the * The whole of the copper is calculated as oxide part being in fact combined with chlorine. VOL. XVII I. G CHURCH ON SOME HYDRATED first part of the present communication has been obtained by Kane and by Graham by the action of water on the com- pound CuH,N,C12 :-Kane’s Salt.. .. .. CuC1,.4CuH202.2aq. New Cornish mineral .. CuC1,.4CuH20,.4aq. The atacamite from Cornwall (St. Just) occurs in a variety of forms. The mineral is sometimes found as hollow stalactitic tubes the concentric layers of which are almost transparent. Sometimes it appears in semicrystalline crusts more or less dis- tinctly stratified and having a rippled surface. The proximity of the copper mine in which the mineral is found to the sea and the detection of sodium and magnesium salts in the atacamite itself point to the mode of its formation. I am indebted to the kindness of Ah. R. Talling of Lost-withiel for all the minerals mentioned in the present note. Notes to the foregoing paper.-Some indications of the existence of another cupric oxychloride more basic than the new species described have been observed Until additional specimens have been met with it would however be premature to make any posi- tive statements on this point.The new oxychloride is not affected by boiling with water. No cupric chloride enters into solution nor is the colour of the mineral altered. An intimate union seems to exist between the ciipric chloride and hydrate in the new mineral. Its formula (omitting the 4aq.) might perhaps be written on a mixed HC1 and H,O type (2HC1 + 8H,O) I have mentioned that the new oxychloride contains a trace of some sodium-salt. It seems to be the chloride and is removed by washing the mineral with hot water. The quantity is trifling. 511 milligrammes of the finely powdered mineral gave by this treatment but 3 milligrammes of silver chloride.I deemed it a matter of some interest to determine the chlorine in the mineral thus washed. Accordingly a portion was dried over oil of vitriol in VQCUO till it ceased to lose weight. Of this preparation ,353 grammes gave ~17 grammes silver chloride. This quantity CGPRIC OXYSULPHATES FItOM CORNWALL corresponds to 11-91 per cent. of chlorine exactly the proportion demanded by the formula I have adopted. All the insoluble basic cupric minerals already alluded to if finely powdered dissolve easily in dilute acids. On this property might be founded a method of volumetric analysis the ratio of chloride (or sulphate) to hydrate being I believe thus ascertainable. Postscript March llth 1865.The new oxychloride occurs in the Botallack mine. Thanks are due to the captain of this mine ah. Hockin for his obliging courtesy. Mr. Talling has now found and forwarded to me a further supply of the new blue oxychloride. Some of the specimens are on quartz. One of the new specimens gave the following results on analysis (substance dried in vacuo) 0264 grm. gave -175 grm. CuO = 66.29 p. c. -3555 grm. gave -235 grm. CuO = 66.10 p. c. Theory demands 66.60 per cent. The chemical and physical characters of this species are therefore constant as well as distinct.