Bibliography. 383 
Siliceous and ferruginous sand,* _ 8780 grs. OFa: 
Silicic acid, ; : ‘ . 23°620 12-275 
Carbonic acid, : : - 8-000 a7e8 18-135. 
Sulphuric acid, : - Ai Lip hs I 0:072 
Lime, . : ; . 47-285 13-281 } 
Alumina, é . 6120 2:941 | 
Peroxide of iron, . ‘ : 3°260 0-998 , 
eine . . 1-920 0-760 ¢ 18:190. 
Manganese (oxide of), ‘ : 0:100 0:077 
Potash, 2 : ‘ . « 0-792 9-133 
100-014 
014 gain, ashes. 
100-000 
Oxygen of the acids=18-135 
Oxygen of the bases=18-190 
** One hundred grains of the Rosendale cement yielded, on analysis, as 
follows :— 
Oxygen. 
Silicie acid, f°" SS 18-170 prs.con. + 9-439 
Sulphuric acid, . ; : 1-000 0-598 12°93 
Carbonic acid, ; é . 4-000 2-893 
Lime, 4 5 , .  44:970 12-630 
Magnesia, ; . : 19-080 7°360 
Alumina, . ‘ ; : 5500 2:563 
Peroxide of iron, . : . 4:900 1501 
Oxide of manganese, . : 1-000 0:464 + 12-291. 
Benen oh enn geo N OST 0-114 | 
Soda, : ; Bs ‘ 0:438 0-112 | 
Water, : , * 0-200 0-177 § 
99-931 
ot oxygen of the acids is, 12-930 
ae ‘6 lime is, 12-630 
&§ gf *¢ other bases is, 12-291 
** From which it would seem that bibasic compounds are formed when 
the cement sets. ; 
**On comparing the analyses with each other, it appears that the chief 
constituents of the Connecticut cement are silica and lime, whereas a 
large proportion of magnesia enters into the composition of the Rosen- 
dale. The inference suggested by the results of the table is thus 
strengthened by those of the analyses, viz. that the increased energy of 
the latter cement may be ascribed to the formation of double silicates. 
‘** Dr. Jackson, who has performed many experiments with hydraulic 
mixtures, informs me, that the oxide of manganese will answer the same 
* The sand is not in chemical combination, but is mechanically mixed with the 
other ingredients of the cement. 
