143 Alloy of Gold u-ith Till.'— AccouittS of Booh. 



Though I vvns perfuaded that tin deprived gold of its great duftillty, or at lead rendei-ed it. 

 fb brittle that it could not be reduced to thinleaves.nor more efpecially be made to pafs the 

 vire plate but by virtue of repeated annealing, and peculiar treatment which gold of the ufual 

 duclility does not require, I neverthelefs determined to repeat the experiments of Mr., 

 Alchoriie, as well from efleem for that Ikilful artift, as to fupply fuch facls as miglit appear 

 t-o have efcaped his notice. 



My firft experiment confided in mixing 24 grains of fine gold with one of tin, taken 

 from an ingot of this laft metal which contains no arfenic. I wrapped this grain of tin in 

 the 24 grains of gold reduced to a very thin leaf, rendered very flexible by annealing. I 

 placed thefe 25 grains upon a piece of charcoal hollowed out, upon vi'hich they could be 

 fupported during their fufion. I even fprinkled a fmall quantity of calcined borax upon 

 the metal, in order that the fuGon might be more fudden, that the metal might ?low toge- 

 ther, and the tin unite vi-ith the gold without allowing time for it to become calcined. 

 This alloy was fpeedily fufed by the enameller's lamp, and reduced into a fmall button 

 without any lofs of weight. It was then flattened carefully beneath the hammer -, but, 

 iiotwithftanding my precaution in this refpecl, it cracked, and at laft broke into three 

 pieces, its thlcknefs then being a quarter of a line or thereabouts. 



I repeated this firfi experiment with a double quantity as well of pure gold as of tin. 

 The refult was the fame. This fecond button was brittle, and likewife broke under the 

 hammer, though I had carefully managed the procefs of hammering in order that this 

 ■ button might have continued whole notwithftanding the cracks. ' 



It is eafily feen that thefe experiments, which were in fome meafure preparatory, tended 

 to intimate the confequences I had reafon to expedl when I (hould repeat them more at 

 large, and in a 'manner more nearly refcmbling the experiments with which I meant to 

 compare them. 



\To be concluded in oitr next-l. 



ACCOUNTS OF BOOKS. 



Philofophical Tranfa£lions of the Royal Society of London, for the Year 1798. Part I. 

 Quarto. 199 pages, with 26 pages of Meteorological Journal, and 7 plates. Sold by 

 Elmfly, London. 



J. HIS part contains the following papers : i. The Bakerian Le£lurc. Experiments 

 upon the Refiftance of Bodies moving in Fluids. By the Rev. Samuel Vince, A.M. 

 F.R.S. Plumian Profeflbr of Aftronomy and Experimental Philofophy in the Univerfity 

 of Cambridge. — 2. Experiments and Obfervations, tending to {hew the compofition and 

 properties of Urinary Concretions. By George Pearfon, M.D. F.R.S. — 3. On the 

 Cifcovery of four additional Satellites of the Georgium Sidus ; the retrograde motion of 

 its old Satellites announced, and the caufe of their difappearance at certain diftances from 

 the planet explained. By William Herfchel, L.L.D. F.R.S.— 4. An Enquiry concern- 

 ing the Source of the Heat which is excited by Friflion. By Benjamin Count of Rum- 

 ford, F.RS. M.R.I.A. (See Philof. Journal II. 106.)— 5. Obfervations on the Fo- 

 ramina Tliebefii of the Heart. By Mr. John Abeniethy, F.R.S.— 6. An Analyfis of the 



earthy 



