Silver. By ROBERT WARINGTON ESP. XCIII. On a curious Change in the Molecular Structure of Mr. Warington on tile Molecular Structure of Silver. 47 TH.E subject of the present brief communicatioii was put into my hands by my friend Mr. Porrett after our last Meeting as bearing on the subject of the memoir which I had the honour of reading before the Society in January 1842% ; a subject I am still prosecuting as my time will permit and the results of which I hope to lay before the Society at an early date. It appears from information furnished me by Mr. Porrett to have been part of a silver funeral vase and was discovered by some labourers about four months since at the depth of seven feet below the surface of the ground while digging for brick-earth between Bow and Stratford.Its height was about ten inches and its greatest diameter about eight inches; it weighed PO ounces and had a smaller vase about the size of a human heart in its interior. When brought to Mr. Ed- wards a watchmaker resident in Shoreditch by whom it was purchased it was without a cover aid the contents had been thrown away with the exception of some black ashes which * See Memoirs vol. i. p. 77. ' 48 Mr. Warington on the Molecular Structure ofSiher. were not preserved. Its thickness was about from 0*015 to 0.0 17 of an inch its surface presented a dull tarnished aspect and was stained in patches with red oxide of iron. I t was extremely rotten and brittle breaking by the application of the slightest force; the surfaces of fracture were uneven and of a hright white metallic lustre.When examined under the microscope by a power magnifying 100 diameters it presented a highly crystalline structure the facets of the crystals being exceedingly bright and approaching the cubic form but none of them could be observed perfectly developed ; they were more analogous to the characters of' grain tin in its broken state :IS met with in commerce. I t appeared also as though there had been a recrFstallization of the metal as the particles looked as if they had been drawn from the central part to the sides of the thin plate leaving cavities or interstices of consirlei-able extent arid depth ; the exterior surface was also coated with B film of about 0.0005 of an inch thick having a grayish-olive coloiir and totally different in its structure from the other parts being striated across its breadth.The specific gravity of the metal in this state was found to be 9937 great care having been taken to remove the air from the internal cavities by means of the air-pump. The metal was next heated to redness in* a crucible and the heat sustained for about ten minutes after which its cha- racters were found to be totally altered ; it had lost its extreme brittleness requiring to be bent ceveral times before a fracture could be effected and then by the aid of the microscope exhibited a close sinall grained tough aspect of a dull white colour and without the previous cavernous appearances ; the superficial film seemed also in places to have partially sepa- rated from the substance of the thin plate of metal during the bending.The specific gravity was a7gRin taken adopting the previous precautions and was found to be 9.95 making an increase of 0.013 or1 the gravity taken before the application of a red heat. I t was next submitted to analysis; 8.5 grains were digested in dilute nitric acid and the soluble parts (A) decanted and the residue well washed. This residue was in small thin grayish-white flakes and by exposure to the light became ra- pidly of cz purple tint indicating the presence of chloride of silver; fearing that this might have arisen from some acci- dental impurity in the materials employed both the nitric ticid and distilled water were carefully tested and proved to be perfectly pure; it was therefore digested in weak solution of ammonia which dissolved the whole with the exception of a small quantity of brown powder which was found to consist 49 of 0.06 gr.of peroxide of iron and a trace of gold. The am- moniacnl solution was precipitated by nitric acid and gave 0.52 gr. of chloride of silver. The solution (A) was next precipitated by solution of chloride of sodiuni arid gave 10.25 grains of chloride of silver equivalent to '7.66 grains of silver ; solution of catistic potash and boiling threw down the oxide of copper and yielded 0.30 gr. oxide of copper = 0.24 gr. of copper. Thus we have- Chloride of silver. . . 0~52 ... . Mr. Arrott O?L a Class of Double Sulphates. Silver . . . . . . '7.66 grains.Oxide of iron . . . . 0*06 ... Copper . . . . . 0-24 ... _- __ Gold . . . . . a trace Loss . 8.48 0.02 -~ 8*50 I t becomes R ciirious question as to the origin of this chlo- ride of silver which was evidently the superficial grayish fillti . observed undrtr the microscope and which partially separated in the act of bending the metal after heating. That it must have been produced by the continued action of cldorides per- haps aided by sulphates present in the brick clay from which the vase was excavated there can be little doubt and the per- oxide of iron also existing in the clay may have assisted this action. The passage of the metal to the brittle state in this and in all other cases will I think be found attributable to some electrical action arising from sudden cooling vibration or concussion chemical acticrn &c.to which the metallic body or alloy may have been exposed. Mr. Warington on tile Molecular Structure of Silver. 47 XCIII. On a curious Change in the Molecular Structure of Silver. By ROBERT WARINGTON ESP. TH.E subject of the present brief communicatioii was put into my hands by my friend Mr. Porrett after our last Meeting as bearing on the subject of the memoir which I had the honour of reading before the Society in January 1842% ; a subject I am still prosecuting as my time will permit and the results of which I hope to lay before the Society at an early date. It appears from information furnished me by Mr. Porrett, to have been part of a silver funeral vase and was discovered by some labourers about four months since at the depth of seven feet below the surface of the ground while digging for brick-earth between Bow and Stratford.Its height was about ten inches and its greatest diameter about eight inches; it weighed PO ounces and had a smaller vase about the size of a human heart in its interior. When brought to Mr. Ed-wards a watchmaker resident in Shoreditch by whom it was purchased it was without a cover aid the contents had been thrown away with the exception of some black ashes which * See Memoirs vol. i. p. 77 48 Mr. Warington on the Molecular Structure ofSiher. were not preserved. Its thickness was about from 0*015 to 0.0 17 of an inch its surface presented a dull tarnished aspect, and was stained in patches with red oxide of iron.I t was extremely rotten and brittle breaking by the application of the slightest force; the surfaces of fracture were uneven and of a hright white metallic lustre. When examined under the microscope by a power magnifying 100 diameters it presented a highly crystalline structure the facets of the crystals being exceedingly bright and approaching the cubic form but none of them could be observed perfectly developed ; they were more analogous to the characters of' grain tin in its broken state :IS met with in commerce. I t appeared also as though there had been a recrFstallization of the metal as the particles looked as if they had been drawn from the central part to the sides of the thin plate leaving cavities or interstices of consirlei-able extent arid depth ; the exterior surface was also coated with B film of about 0.0005 of an inch thick having a grayish-olive coloiir and totally different in its structure from the other parts being striated across its breadth.The specific gravity of the metal in this state was found to be 9937 great care having been taken to remove the air from the internal cavities by means of the air-pump. The metal was next heated to redness in* a crucible and the heat sustained for about ten minutes after which its cha-racters were found to be totally altered ; it had lost its extreme brittleness requiring to be bent ceveral times before a fracture could be effected and then by the aid of the microscope, exhibited a close sinall grained tough aspect of a dull white colour and without the previous cavernous appearances ; the superficial film seemed also in places to have partially sepa-rated from the substance of the thin plate of metal during the ' bending.The specific gravity was a7gRin taken adopting the previous precautions and was found to be 9.95 making an increase of 0.013 or1 the gravity taken before the application of a red heat. I t was next submitted to analysis; 8.5 grains were digested in dilute nitric acid and the soluble parts (A) decanted and the residue well washed. This residue was in small thin grayish-white flakes and by exposure to the light became ra-pidly of cz purple tint indicating the presence of chloride of silver; fearing that this might have arisen from some acci-dental impurity in the materials employed both the nitric ticid and distilled water were carefully tested and proved to be perfectly pure; it was therefore digested in weak solution of ammonia which dissolved the whole with the exception of a small quantity of brown powder which was found to consis Mr.Arrott O?L a Class of Double Sulphates. 49 of 0.06 gr. of peroxide of iron and a trace of gold. The am-moniacnl solution was precipitated by nitric acid and gave 0.52 gr. of chloride of silver. The solution (A) was next precipitated by solution of chloride of sodiuni arid gave 10.25 grains of chloride of silver equivalent to '7.66 grains of silver ; solution of catistic potash and boiling threw down the oxide of copper and yielded 0.30 gr. oxide of copper = 0.24 gr. of copper. Thus we have-Silver . . . . . . '7.66 grains. Chloride of silver. . . 0~52 ... Copper . . . . . 0-24 ... Oxide of iron . . . . 0*06 ... Gold . . . . . a trace . 8.48 Loss . 0.02 8*50 _- __ -~ I t becomes R ciirious question as to the origin of this chlo-ride of silver which was evidently the superficial grayish fillti . observed undrtr the microscope and which partially separated in the act of bending the metal after heating. That it must have been produced by the continued action of cldorides per-haps aided by sulphates present in the brick clay from which the vase was excavated there can be little doubt and the per-oxide of iron also existing in the clay may have assisted this action. The passage of the metal to the brittle state in this and in all other cases will I think be found attributable to some electrical action arising from sudden cooling vibration or concussion chemical acticrn &c. to which the metallic body or alloy may have been exposed