Observations on the rare earths : yttrium chloride and the atomic weight of yttrium . issolved with violent reaction in one liter of water. This was heated to boiling la a large retort and a stream of steam passed thru to keep the solution well stirred while a ten per oent. solution of potassium ohromate was added a drop at a time. The earth was split up into about six fraotions and in this way some fairly pure yttria was prepared in a rather short time. 22 ) In the same year Muthmann and Bauer used the method together with theammonia preo ipitation and obtained yttria free from erbium but con
Observations on the rare earths : yttrium chloride and the atomic weight of yttrium . issolved with violent reaction in one liter of water. This was heated to boiling la a large retort and a stream of steam passed thru to keep the solution well stirred while a ten per oent. solution of potassium ohromate was added a drop at a time. The earth was split up into about six fraotions and in this way some fairly pure yttria was prepared in a rather short time. 22 ) In the same year Muthmann and Bauer used the method together with theammonia preo ipitation and obtained yttria free from erbium but containinggadolinium. 23) From 1900 - 1902 BBhm made a study of the efficiency of the methodas applied to the cerite-elements and found that the fractionation proceededin the following order: 1. Cerium earths - Ce, La, Pr, Nd, Sa. 2. Yttrium earths - Tb, Yb, 2r, Y, Sd. 24 ) Dennis and Dales in 1902 used the method of Kruss and Loose, andMoissan and obtained yttria with an atomio weight of 94 in a rather shorttime, but they decided however that the method was inefficient for the other. -7- earths. 26 ) Also in the same year Hoffman and Zerban oaused the radioactivity ofthorium preparations to rise by fractionally precipitating them with potas-sium chromate . B. Experimental. In using the chromate method for fractional separa-tion the ignited oxides were mixed dry with the calculated amount of chromicacid by shaking in an eight liter round bottom Jena flask, and then addingabout 200 oc. of water. A violent reaotion resulted, the dichromates beingformed with the evolution of much heat. The whole was diluted to four litersand a ten per oent. solution of potassium chromate added until a permanentoloudiness resulted. The flask was then heated to boiling over a sand bathand, while vigorously stirred by passing a current of steam through the solu-tion, a ten per cent, solution of potassium chromate was added drop by dropfrom a separatery funnel, various amounts being added according to th
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