30 VI.-On mme Physical Properties of the Alloys of Tin and Lead. By PROFESSOR Bo L LEY. At the Conference of the Chemico-Technical Scction of the Swiss Polytechnic School at the end of the session 1858-9 the following prize problem was offered for solution the award to bc made in May 1861 :-1. A survey of all researches hitherto published on the physical propertie~-especially the hardness fusibility and specific gravity of the alloys of tin and lead. 2. Preparation of nine alloys containing definite equivalent quantities of these elements viz. :-1 equivalent of tin to a 4 4 % 1 l+ 2,3,and 4 eq. lead. 3. Determination of the specific gravities and melting points of these alloys ; also of their relations as elements of a simple voltaic circuit in connection with tin lead and ziuc and in presence of acids alkaline liquids and dilute saline solutions.The prize was .awarded to G. Pillichody of Bern from whose Essay we here extract the most interesting results. The experiments were made in the Technological Laboratory of the Institute. a. Specific Gravity.-From a comparison of the researches of Kup ffer Long and Tho rn p son it appears that the specificgravities of the alloys of tin and lead exhibit considerable variation. The author'^ determinations agree most nearly with those of Long. He found in accordance with Kupffer that the specific gravities of these alloys as determined by experiment are smaller than the mean values calculated from the quantities and specific gravities of the component metals; but that (contrary to Kupffer's statements) the expansion-that is to say the difference between the observed and calculated densities-is greatest in the alloy SnPb so that with an increase in the proportion of either metal the specific gravities as determined by experimeut and by calculation approach more nearly to each other.IIOLLEY OX ALLOYS OF TIS Axil) LEAD. TIicsc rclutiom wc cx1iil)itcd in t'iic fdhviiig tablc :-Pillichodj. . 01,s. Cult. Sa Pb .. Sn 1% .. Sn 1% .. Sn l'b .. Sll PI1 ..... Sn .. Sn PI) . SI1 1'5 . su 1'). . The author's results atford bn additional proof that very little deixmdcnce is to be placcd 011 the hydrostatic mctliod for the determination of the composition of lcad and tin alloys.b. Melting points.-'Phc statcments of difl'crciit authors respcct- ing the melting points of the alloys of tin and lead cshibit even grcatcr discordance thn thosc which relate to the specific gravities. Most of thosc who occupicd themsclves with thc subject prior to tlie investigations of ltudbcrg or without knowledge of those investigations neglccted to obscrvc a very important circum- stance perhaps the most jritcresting of all corinectcd with it. This circumstance is casily overlooked if only the melting point be obscrvcd instcad of tlic solidifying point which givcs much morc trustworthy rcsults. Whcii the lattcr method is followed the tbcrmomctcr immcrsed in thc melted alloy usually exhibits during the passagc of the mass from the liquid to the solid state two stationary points.This effect is due to the separation of ouc or other of the compouent metals while an alloy of constant composition still remains liquid. This alloy has thc coxnpositioii Sn,l'b. An alloy 'richer in lead would first dcposit lcad and an alloy containing il larger proportion of tin would first dcpsit tin-the alloy Sn,Ph. remaining liquid for a longcr or shorter timc and ultimatcly solidifying at about 181' C. Tliis tcini)eratnrc thc-refore corrcsponda to the lowest melting BOLLEY ON ALLOYS OF TIN AND LEAD. point that can be exhibited by an alloy of tin and lead a largcr proportion of either metal caiiscs the melting poiiit to rise. Rudberg determined oiily the intervals of time which elapsed during the fall of temperature through each 10°C.He also employed a thermometer the zcro of which according to his own statement hail not been exactly determined. Pilli ch ody’s experiments on the other hand were made with an exact ther- mometer arid with all the precawtions reqiiired in observations of this kind. In all these detern1inations the constant solidifying point was found to be exactly 181°C. Tuble of the Melting Poi)ils of Allop of Tin and Lead. Pillichody. Rudberg. Thomson. Kupfler. Parkes for Sn4 Pb ........ 187 190-180 190 189 (9 Sn+4 Pb)Ii3 Sn3 Pb ........ 181 190- 180 182.8 186 16893(6 +4) Sn2 Pb Sn3 Pb2 ........ ........ 197 210 210-200 - 182.8 - 196 - (;A42 Sn Pb Sn2 Pha Sn Pbz ........ ........ ....... 235 246 270 250-240 -280 -290 182.2 - 24 1 -289 (47 7)215.7 243.3 (4 +14) (4 +10) Sn Pb3 Sn Pb ....... ........ 283 292 290 -280 - - 254.4 269.4 (4 i-28) (4 f 22) 275 This Table shows that Thorn son who probably also sought for the solidifying point overlooked the variable and observed the thermometer in the neighbourhood of the constant solidifying temperature. Of this constant point no notice is taken either by Prtrkes or by Kupffer.