Appendix.] MODIFIED by COMPRESSION. 183 



This view derives fome confirmation from an infpection of 

 Columns VI. and VII. ; the firft of which exprefles the abforp- 

 tion ; and the fecond, that refult, reduced to a per centage of the 

 original weight. It there appears, that whereas chalk abforbs 

 23.97 P er cent "> fc> m e of our refults abforb only 0.5, or fo low 

 as o. 1 1 per cent. So that the power of abforption has been re- 

 duced from about one-fourth, to lefs than the five hundredth of 

 the weight. 



I have meafured the diminution of bulk in many cafes, par- 

 ticularly in that of No. II. The chalk, when crude, ran to the 

 75th degree of Wedgwood's gage, and fhrunk fo much during 

 the experiment, that it ran to the i6i ft - ; the difference amount- 

 ting to 86 degrees. Now, I find, that Wedgwood's gage tapers 

 in breadth, from 0.5 at zero of the fcale, to 0.3 at the 240th 

 degree. Hence, we have for one degree 0.000833. Confequently, 

 the width, at the 75th degree, amounts to 0.437525 ; and at 

 the 16 1 ft, to 0.365887. Thefe numbers, denoting the linear 

 meafure of the crude chalk, and of its refult under heat and 

 compreflion, are as 100 to 83.8 ; or, in folid bulk, as 100 to 

 57.5. Computing the denfities from this fource, they are as 

 1 to 1.73. The fpecific gravities in the Table, of the chalk, and 

 of this refult, are as 1.551 : 2.435 ; that is, as 1 to L57. Thefe 

 conclufions do not correfpond very exactly ; but the chalk em- 

 ployed in this experiment, was not one of thofe employed in de^- 

 termining average fpecific gravity in the Table ; and other cir- 

 cumftances may have contributed to produce irregularity. 

 Comparing this chalk with refult fecond, we have 1.55 1 : 2.575 

 fo 1 : 1.6602. 



TABLE 



