362 . ANNUAL REPORT 
Other physical and chemical constants determined by Dr. R. and 
Dr. W. Fresenius are given in the following table :* 
1 2 3 4. 5) 
S Bees Sins) 5B 
Description. a Ee AE a my: 2 o 4 
ee. mg. mg 
Portland cementA| 3.155 1.58 6.25 20.71 0.79 1.4 
‘ Bh Sew | Ose. GDN Ol BO | Be 1.6 
c ON Bitsy POO TP AG) ol wes | O28 1.8 
c CO BALA Oe | a0 | Ley | ie 1.0 
c eT, AA i) BN - 1@.GD | 0.98 1.6 
cc Ga Te PO OA aol fay) | 11 aa ial 
“ HEE SMA Ogi | A.A | 2.90 | O89 0.0 
“ TE BIDS | hl | 290 | eO.e0 | iW .or 0.7 
« oi Sige ON) 1 AO 4 140 2.0 0.0 
c C1) Bow | O24) 2a B.70 | 0,98 0.0 
“ BT Slat Ne) | AL) | TS |) BLO 0.3 
“ CM) Bb | 195 | BS0 |) 20.50) 228 0.0 
EFFECT OF VARIOUS REAGENTS ON PORTLAND CEMENT. 
Since Portland cement is a very basic material, it is quite evident 
that it is readily attacked by acids and we find that even weak organic 
acids may exert a powerful solvent action upon this material. When 
mixed with sand, however, and especially if the resulting mortar is dense, 
the action is much less evident than on the neat cement. Even carbonic. 
acid, carbon dioxide in solution in water, is able to act upon cement quite 
strikingly. On the other hand, salts show varying effects, as will be 
illustrated by a table. In common with colloids, hydrated cement has the 
property of taking salts from solution and of holding them by virtue 
of surface. absorption, so that the concentration of such salts is greater 
in the colloid (hydrogel) than in the solution. 
Gases like carbon dioxide, hydrogen sulphide, act upon cement 
quite energetically. Thus Tetmayer found that by storing four cements 
in air and in pure carbon dioxide the average tensile strength of 
*R. K, Meade, Examination of Portland Cement, p. 167. 
