HYDRATES AND CARBONATES OF THE ALKALI-METALS, ETC. 437 



bath kept at 50°. The digestion was continued for six hours ; during the first two 

 with frequent agitation. The withdrawing of the samples was effected exactly as in the 

 case of the experiments at 100°. As in these, silica was found to have passed into the 

 lithia sulphate ; it was allowed for as before. Results : — 



In Solution saturated at 50°. 



x- • . Percentage of Percentage of Li,0 + 3H,0 per 



Experiment. ^ Li 2 0+3H 2 0. 100 of water! 



I. . . 7-25 20-30 25-46 



II. 7-24 2026 25-40 



III. , 7-21 20-16 25-26 



IV. . . 727 20-33 25-52 



Mean, . . 7"24 20-26 25-41 



Summary of Results. — 100 parts of solution saturated at "t°" contains "y" parts 

 of Li 2 as hydrate; hence, in it, 100 parts of water are combined with "S" parts 

 the compound of Li0 2 + 3H 2 0. 



m . Values of y. Mean of the r ■., 



Temperature. Minimum. Maximum. Adopted Values. S from Mean y. 



0° . . 5-61 6-32 5-74 19-15 



19°-4 . . 5-72 6-74 670 23-06 



50°-0 . . 7-21 7-27 7-24 2541 



100°-0 . . 9-26 9-39 9-33 35-32 



When I entered the t's as abscissae and the mean y's as ordinates in a system of 

 rectangular coordinates, I found that the four points suggested a curve, of which I found 

 it difficult to admit that it represented the true relation, because it would have demanded 

 a parabolic function of the third degree to translate it into an equation. I besides 

 remembered, that the experiments at 0° had hardly had justice done to them in the sense 

 of sufficient agitation of the mixture of crystals and water. Neglecting the y for 0°, the 

 other three were found to fall in very well with eq. y = 6 '6375 — 0'002825£ + 0'0003f. 



The constant term is almost identical with the one rejected value for 0°, which 

 strongly suggests that this may be the best value of the set after all. Of course the only 

 way of deciding this question was to repeat the determinations at 0° with greater care. 

 We accordingly did so, and, to make sure of everything, we repeated also the determina- 

 tions at 19° "4. Only, as the carbonic acid in the solutions prepared at these temperatures 

 amounts to very little, we omitted its determination this time, and only allowed for it by 

 calculation, assuming that the weight of Li 2 present in a given solution prepared at 0° 

 and 19° *4 respectively, per unit- weight of total Li 2 0, is the same as the corresponding- 

 average for the determinations previously made at 0° and 19° '4 respectively. The 

 experiments at 0° were conducted in the following manner : — 



I. 3*32 grm. of crystals, and 10 c.c. of boiled-out water were heated up to, and for an 



VOL. XXXV. PART II. (NO. 12). 4 D 



