436 PROFESSOR W. DITTMAR ON THE BEHAVIOUR OF THE 



Thinking that No. IV. was affected with an unobserved error, I adopted the mean of 

 I., II., and III., which is : — 



5-74 1607 19-15 



Experiments at 100°. — These were carried out as follows : — 4*6 grm. of lithia-crystals 

 and 10 c.c. of boiled-out water were placed in a test-tube, which was then suspended in a 

 steam bath, to establish and maintain a temperature of 100°. A " Thorpe stirrer" within 

 the test-tube served to mix up the contents. The test-tube was provided with a per- 

 forated cork, and the stem of the stirrer passed through a short bit of indiarubber 

 tubing slipped over a short piece of glass tube accommodated in the perforation of the 

 cork, so that the stirring could be done while the test-tube was closed. During the first 

 hour the contents were being constantly agitated ; the stirrer was then withdrawn, and 

 the contents allowed to clear up for five hours, at 100°. A small quantity of the 

 clear liquor was now withdrawn by means of a hot pipette, the pipette with its contents 

 quickly transferred to a test-tube containing some water, and the whole weighed. By 

 subtracting the conjoint weight of pipette, added water and test-tube, we obtained the 

 weight of the sample of solution taken out, which was analysed as usual. In the first 

 experiment two samples were drawn — one after five hours' standing, another forty-five 

 minutes later (Determinations I. and II.). In the second experiment a similar method was 

 followed ; only, after withdrawing a sample of the clear liquor for Determination III., an 

 additional small quantity of crystals, and a corresponding quantity of water were added 

 to the residue, the whole heated for five hours and then a sample of clear solution taken 

 out for Determination IV. 



When the sulphates of lithia were dissolved in water, a little silica was found to re- 

 main in each case. This was filtered off and weighed, to be allowed for in the calculation. 

 The silica amounted to about ^tnrth of the sulphate of lithia ; as it no doubt came out of 

 the glass, the glass-alkali which accompanied it ought to have been determined, but I 

 could not see my way to doing this satisfactorily, and therefore simply neglected it. 

 The results were as follows : — 



In Solution saturated at 100°. 



Experiment. 



Percentage of 

 Li 2 0. 



Percentage of 

 Li 2 + 2H 2 0. 



Li 2 + 3H,0 



100 of Wat 



I. 



932 



26-09 



35-29 



II. 



9-39 



26-26 



35-62 



III. 



9-26 



25-92 



3499 



IV. 



9-34 



2614 



35-38 



Mean . . 9-33 2610 35"32 



Experiments at 50°. — In these the saturated solutions were prepared pretty much in 

 the same way as in the 19° '4 experiments, viz., by shutting up the crystals with an 

 insufficiency of boiled-out water in a close bottle, which was then immersed in a water- 



