Febniary 6th, ipi2.] rKOCEEDINGS. xxix 



with a silver salt), finally produced the so-called English silver- 

 lustre pottery, which is pottery coated with a shining surface of 

 platinum. 



The method by which this surface was obtained is exceedingly 

 simple. A solution of platinum in aqua regia was slowly 

 poured, with careful stirring, into about three times its bulk of 

 an oily menstruum, such as balsam of sulphur or spirits of tar. 

 This forms an oily pigment which can be applied to a piece of 

 glazed pottery so as to obtain a uniform coating. When the 

 oily coating has become tacky by drying, a film of finely divided 

 platinum, obtained by charring ammonium-platino-chloride, is 

 dusted upon it, and when the ware is again fired at a low 

 heat, say 7oo°-8oo° C., a brilliant metallic deposit of platinum is 

 found fixed to the glaze. 



This pottery has always been known as silver-lustre^ though it 

 has no more right to the name " lustre " than to that of " silver." 

 The term "lustre" as applied to any pottery decoration should 

 be definitely restricted to those films of silver, copper or gold 

 which are so thin as to exhibit interference colours like a soap- 

 bubble does. Some years ago I suggested for this form of 

 English pottery the term " plated ware," as it was so obviously 

 intended to be a cheap substitute for the silver plate of the 

 period. The shapes of the articles manufactured were mostly 

 copied from the popular Sheffield plate of the day, and the new 

 pottery was so successful that by about 1800 the process was 

 being followed at ten or a dozen factories in the Staffordshire 

 potteries, as well as at the famous potteries at Leeds and else- 

 where. Gradually it lost its popularity, and by about 1850 had 

 almost fallen into disuse ; but within the last few years the 

 method has been revived, and is now extensively employed both 

 by English and Continental firms for pottery decoration. 



Professor Ernest Rutherford, D.Sc, F.R.S., read a 

 paper on "The origin of the /3 rays from radio-active 

 substances." He said that irom a study ot radio-active 

 transformations it has been found that each atom of matter in 



