The London, Edinburgh and Dublin philosophical magazine and journal of science . m the same locality have also been made for thesake of comparison. The following is a description of the method used and theresults obtained :— method used for the estimation of radium was a modi-fication of Joly^s fusion method (Phil. Mag. xxii. 1911,p. 134). It is perhaps not capable of quite general application,but it proved very efficacious for all the rocks dealt with inthe present experiments. The principle consisted in thefusion of the rocks with potassium hydroxide under reducedpressure; a
The London, Edinburgh and Dublin philosophical magazine and journal of science . m the same locality have also been made for thesake of comparison. The following is a description of the method used and theresults obtained :— method used for the estimation of radium was a modi-fication of Joly^s fusion method (Phil. Mag. xxii. 1911,p. 134). It is perhaps not capable of quite general application,but it proved very efficacious for all the rocks dealt with inthe present experiments. The principle consisted in thefusion of the rocks with potassium hydroxide under reducedpressure; and the results obtained appear to show that bythis means the radium emanation is liberated just as com-pletely as by the higher temperatures necessitated by fusion * Communicated bv the Authors. Radioactivity of Rocks of the Kolar Gold-Fields. 45 with alkaline carbonates. A thick copper flask A, of about300 capacity, with a long neck upon which was solderedan outer tube to form a water-jacket, was used to effect thedecomposition. 10 grams of the rock, powdered so as to. pass through a 120-mesh sieve, were mixed with 2 grams ofanhydrous sodium carbonate and introduced into the flask,and 50 grams of stick potassium hydroxide added. The lastwas not fused to remove water previous to use, as it has beenshown that vigorous ebullition assists in the liberation of theemanation. The flask was then connected to the rest ofthe apparatus as shown, by a rubber stopper, and the wholeevacuated with a Fleuss pump to a pressure of about 1 cm.,as shown by the small manometer K. The tap B was thenclosed and the flask and contents heated with a large Tecluburner for 15 minutes, a very rapid stream of water beingpassed through the neck. A certain amount of gas wasusually liberated, and in the earlier experiments the pressuresometimes rose to such an extent that the cork was blown outof the flask. To avoid this, a safety-valve was devised. Thetube E, slightly greater in length than the barome
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Keywords: ., bookcentury1800, bookdecade1840, booksubjectscience, bookyear1840
