438 PROFESSOR W. DITTMAR ON THE BEHAVIOUR OF THE 



hour kept at, 50° with occasional agitation. The stirrer was now removed, the tube closed, 

 and kept in a double ice-bath (vide supra) for twenty hours. Two successive portions of 

 the clear liquid were drawn off with a pipette, weighed and analysed for Li 2 by evapora- 

 tion with sulphuric acid, &c. The resulting percentages of Li 2 were, A = 6*713 

 and B = G'687. 



II. 1*56 grm. of crystals and 5 c.c. of boiled-out water, both previously cooled in ice, 

 were mixed in a test-tube standing in an ice-bath, and agitated constantly for forty-five 

 minutes. The stirrer was then removed, the tube closed and kept within the double ice- 

 bath for twenty hours. Two successive samples were then drawn off, and their lithia was 

 determined as sulphate. The resulting percentages were C = 6700 and D = 6708. In 

 the case of C there was a slight loss; the mean of the other three numbers is 6703. 

 By applying the correction for carbonic acid, I obtained for the corrected number the 

 value 6-667. 



Tlie New Experiments at 19° - 4. — I. The residue of crystals and solution saturated at 

 0°, left after withdrawal of sample " B," was mixed with an additional half-gramme of 

 lithia-crystals, the whole heated up to 50° and kept at this temperature for half an hour 

 with constant stirring. The tube was then transferred to a water-bath kept at 19° '4, its 

 contents constantly stirred there for about two hours, and then left at rest in the same 

 bath for six hours, when the liquid was found to have cleared up completely. Two 

 successive samples, E and F, were then withdrawn, and their Li 2 determined as usual. 



II. The residue left after withdrawal of sample D at 0°, after having been supple- 

 mented by addition of a little water and a corresponding (excessive) quantity of crystals, 

 was kept at 19 0, 4 for eight hours; during the first two with continual stirring. Two 

 samples, G and H, were then sucked out and analysed. Eesults : — 



E f G H 



y = 6799 6-802 6798 6798 



Mean = 6799 ; or 6738 after correction for the carbonic acid. 

 The new values for y at 0° and 19°'4, together with the old ones at 50° and 100°, 

 fall in well with the formula : — 



y = 6-6750 — 0-00346Z + 0*0003^, as seen from the following comparison : # — 



¥ort= 0° 19°-4 50°-0 100° 



y by calculation, . 6-675 6721 7-282 9-327 



y by experiment, . 6-667 6-738 7-240 9-330 



For the preliminary determination of the solubility of caustic lithia in alcohol, a 

 quantity of the crystals was kept in contact with alcohol of 97 per cent, by weight for 

 six hours, at a temperature of 15° established by means of a water-bath. During the 

 first two hours the mixture was being agitated occasionally, during the last four it was 

 allowed to clear up. In weighed portions of the clear liquor the lithia was determined as 



* According to this formula there should be a minimum of solubility at < = 5 0, 77, and at ll 0- 54 the solubility 

 should be the same as at 0°. At 5°-77, by calculation, y = 6-665. It would take very exact work to see whether this 

 minimum has any existence outside the formula, which latter of course does not pretend to formulate the actual law in 

 the relation between t and y. 



