156 Transactions.—Miscellaneous. 
great. 7 If it is possible to ram ‘“betou agglomeré” into a third of its 
original bulk, it is quite obvious that the voids in the unpressed article 
must equal or exceed the solid parts, or that the whole mass lacks the 
density essential to strength and impermeability. A coat of plaster on the 
outside of a building will not, as is sometimes supposed, effectually keep 
out damp. At the most, Portland cement and its mixtures are only lime- 
stone or calcareous sandstones or grits, and, as such, are more or less 
absorbent ; it is, therefore, necessary to convert them into the compact 
state by pressure, if we want it to resist moisture, and it is impossible to do 
so in plastering. 
Although some thousands of experiments have within the last few years 
been made to determine the strength of Portland cement and its mixtures, . 
under every conceivable circumstance, there is no record of any regular 
experiments having been made to test its powers of resisting damp. 
General Gillmore made one or two trials of ‘‘betou agglomeré,” and he 
pronounces it to be practically impervious; the amount of moisture 
absorbed in four days was immeasurably small. 
An Indian engineer, Mr. Horace Bell, found that neat Portland cement 
absorbed 20 per cent. of its weight in an hour, and 25 per cent. in three 
hours. In view of the paucity of our information on this subject, I made a 
few experiments with samples in my possession. The specimens were not 
prepared for this purpose, so the proportions of the various ingredients and 
mode of mixing them were not recorded with the exactness necessary in @ 
thorough investigation ; the results are, therefore, not advanced as abso- 
lutely conclusive. 
Weig ght of water 
absorbed after 24 
hours’ immersion. 
Neat Portland Cement.—Lump taken from a 
damaged cask, the original powder having ben} 2 per cent. 
consolidated by hydraulic pressure... 
Neat cement from the Rangitata bridge, four 
years old; it had been pressed into a on 63 ” 
with a Gonal like ordinary mortar 7 
Neat cement, another sample like the last ce 
Cement mortar, from Abbotsford bridge, sigs 9 
years old, 1 of cement to 8 of coarse sand... 
Concrete, one year old, made from 1 of cement to 
7 of tailings, the sizes of the ingredients wa 4} 
well adjusted, and the conerete very compact 
Another experiment was made with a specimen block of conerete, made 
bP 
by the proprietors of the Logan Point Quarry. It was composed of one of 
