506 Messrs. Play fair and Joule on M. 



I. NaO, HO, 2CO2, vol. of salt 38-8 ... 

 II. ... ... 38-4 ... 



Mean . 



2-181 

 2-204 



. 38-6 ... 2-192 

 Although we have examined other carbonates, we purposely 

 avoid bringing them into the present paper, because they in- 

 volve considerations upon which we are at present engaged 

 in minute study, and do not wish to hazard without sufficient 

 proof. We subjoin the few carbonates here examined in a 

 tabular lorm. !, . . ., 



Table XL — Showing the Volumes occupied by the Alkaline 

 Carbonates. 



The results shown in this table will appear perplexing, 

 unless the facts already observed in the previous sections be 

 borne in mind. We find in carbonate of potash an astonish- 

 ing difference between the liquid and the solid volume ; and 

 this is still more marked in the case of carbonate of soda, 

 which ceases to occupy volume in solution. Both of these 

 salts have 11 as the divisors of their solid volume, KO, COg 

 affecting three, and NaO, COg two volumes. In the last section 

 we saw that the three volumes possessed by chromate of potash 

 in its solid state passed over into bichromate of potash ; and 

 in bicarbonates of potash and ammonia we observe the same 

 circumstance, except that the volumes change from multiples 

 of 11 to multiples of 9*8, and in solution are one less than in 

 the state of a salt. It is probably owing to this circumstance 

 that we do not in this case observe the usual increase of one 

 volume in the ammoniacal over the corresponding salt of pot- 

 ash. The bicarbonates of potash, soda and ammonia are pro- 

 bably multiples of 9-8, or the volume of ice. 



Vol. by experiment. Vol. by theory. 



Bicarbonate of potash . 49-0 .. 2*052 .. 9-8 x 5 =49-0 .. 2*052 

 ammonia 50*0 .. 1-586 .. 9*8 x 5 =49-0 .. 1-618 

 soda . . 38-6 .. 2-192 .. 9-8 x 4 =39-2 .. 2-159 



