it ll V 64 Circular N0. 9. ‘ _· l
V. V corresponds to the percentage of calcium carbonate inthe  
` . V limestone. 5 p » — if
  V ~ The cylinder "K" was graduated to read per cent by .. ' ._
i T treating one gram of chemically pure calcium carbonate as l
... - just described to find the position of the 100 per cent mark.
A . T The position of the 50 per cent mark was determined in the ‘
j same way. by using é gram, and the space between the100
`_ per cent mark and the 50 per cent mark was divided into 50
_ equal parts. _ , ·
. V Fifteen different samples of limestones which had been
` previously analyzed by a more exact quantitative method .
· were run with the apparatus described above. The follow-
 ` ing table shows the results obtained by the two methods:
_ . Lab. No. N0. 1 No. 2 Variation ·' `
* ` A — CaCO:; _CaCOs L
7 50422 98.61 per cent 98.80 per cent . + 0.18 per cent
l 50423 _ 89.50 " 89.80. V " —l» 0.30 "
  . 50429 82.00 " 80.50 " — 1.50 " V
i 50430 77.62 " 76 50 " -— 1.12 "
,' 50431 67.87 " 66.50 " ~— 1.37 "` L
. ` 50432 87.25 " 86.50 ' " — .75 _" » V
50433 95.87 " 96.00 " + .13 "
C 50434 99.00 " 99.00_ " .00 "
.— 50435 96.62 " 96,50 " V —— .12 "
. 50436 97. 50 " 96.00 " — 1.50 "
50445 59.29 " 61.00 ‘_‘ »l— 1.71 " V
. 50447 86 25 *‘ 84.25 " — 2.00 "
50450 100.25 " 99.90 " — 1.25 "
50451 _ 94 25 " 93.50 " — 0.75 " -
50452 98.00 " I 97.00 " V -— 1.00 "
Average U- 88.65 per cent 88.06 per cent
· _ The results in column N0. 1 were obtained by Mr.
Pfanstiel of this laboratory by quantitative chemical
  analyses. The results in column No. 2 were run by the
‘ V apparatus as described in this circular. _
. Comparing the results in columns No. 1 and No. 2, we find .
· 4 variations from 0 to 2 per cent on a single determination in
each case. The average of column No. 1 is 88.65 per cent
' and column No. 2 is 88.06 per cent, which shows fairly close (
~ average agreement. 1
The volume of water displaced by the carbon dioxid will
  vary somewhat, depending on changes in temperature and ‘