44(5 PROFESSOR W. DITTMAR ON THE BEHAVIOUR OF THE 



The carbonate had fused into a white mass, which was smooth and glassy on its surface, 

 but full of small holes on the other side where it had been in contact with the boat. 

 0416 grm., when analysed by means of chloride of barium, was found to be neutral. 

 0*8390 grm. gave 0*5000 of carbonic acid, equal to 59*594 per cent. The number 

 calculated from the formula Li 2 C0 3 is 59*427, if Li be taken as =7*02, = 16. The 

 analysis, as we see, gave about 0*16 per cent, more, although our preparation could not be 

 presumed to be absolutely free from foreign bases, and any of these of course was bound 

 to depress the percentage of carbonic acid. Admitting that the difference of 0*16 per 

 cent, was not merely an observational error (need I say that I did not by any means 

 feel sure on this point ?), the experiment would prove that Stas's number for Li (7*02) is 

 a little too high, because there can be no reasonable doubt that Dumas and Stas's value 

 44 for CO2 is practically free of error. Combining what I had found with the fact that 

 both Mallet and Teoost, in 1857, by the analysis of the chloride with nitrate of silver 

 found values for Li which lay decidedly below 7*00 (see Lothar Meyer and Seubert, 

 Atomgeivichte der Elements, p. 225), I deemed it worth my while to prepare normal 

 carbonate of lithia in the way described on a large scale, to analyse it with the requisite 

 degree of precision, and to see what would come out. We accordingly repeated 

 Experiment V. a sufficient number of times to obtain a sufficiency of material and then 

 analysed the carbonate in the following fashion. To avoid repetition let me premise 

 the statement that the same method was used for all the carbonic-acid determinations 



quoted below as "A," " B," "C" "Q," and considered in connection with the 



question of the constant " Li." 



A known weight of the carbonate (about 5 grm.) was decomposed with dilute 

 sulphuric acid in a flask provided with an inverted condenser (Classen's method), which 

 by its outlet communicated with (1) a large chloride of calcium tube for the absorption 

 of the water; (2) a Liebig's bulb-apparatus, # charged with a solution of caustic potash in 

 its own weight of water; (3) a medium-sized U-tube filled with granulated soda-lime, and 

 (the greater part of the outlet-limb) with granulated chloride of calcium of the same kind 

 as that used for (l) ; and (4) one or two smaller U-tubes charged with soda-lime and 

 chloride of calcium like No. (3), to serve as " witnesses" of the complete absorption of the 

 carbonic acid. In the first two analyses (quoted below as A and B) only one witness- 

 tube was employed. It gained 0*5 and 1*2 mgrm. per gramme of substance analysed 

 respectively. This is not much, but it is more than can be neglected in an atomic- weight 

 determination ; I therefore, in the subsequent analyses, added a second witness-tube. 

 This second tube gained weight, per gramme of carbonate analysed, to the extent of — 



0*1 mgrm. or less in nine cases, 

 0*31 to 0*11 mgrm. in three cases, 

 1*64 mgrm. in one case, and 



2*7 mgrm. in another case, namely, the case of analysis of " Q (3)" which was rejected on 

 other grounds. 



* On the occasion of these analyses I invented an improved form of the LlEBlG bulbs, which is described and 

 figured in the Hoc. Clitm Inch Jour, and also in the Chernilcer Zeiturtg, for 1888. 



