68 
Observations , S^c. 
[March, 
14. • If considerable effervescence takes place, it may either have been underburn- 
ed, or what is more probable, it may have become stale by exposure to air, 
through a defect in the cask or otherwise. 
15. If the cement powder be gritty, separate the coarser parts by washing, and by 
decantation, or by filtering, and let them stand in a moist state for a few hours. 
Subject the sand thus obtained to the diluted muriatic acid. If it do not effervesce 
in the acid, the cement has evidently been adulterated by common silicious sand 1 * * * * . 
16. If the coarser parts of the cement should be acted upon by the acid, after the 
above treatment, it is a proof that the calcined cement has not been properly pul- 
verized. 
17. If the cement from the cask, be in the state of impalpable powder, and 
effervesce very little or not at all, in a diluted acid, the chances are, that it is good. 
Make it up into a moist ball, with a moderate quantity of water, and it ought to 
heat in a few minutes, and become exceeding hard. If these effects do not take 
place, it must have been overburned, and is good for nothing. 
IS. The cement powder that heats and indurates in a few minutes after being 
taken out of the cask, will be unfit for present use, from this very circumstance, 
which proves its superior excellence. You must, therefore, either dilute it well with 
watei in using it, or let it previously stand some days exposed to dry air, to pre- 
vent it from setting too rapidly. That which sets in about half an hour, and with 
moderate warmth, is in the best state for general purposes. 
19. If the cement from the cask be in the state of impalpable powder, but effer- 
vesce with acids, with a partial solution of the powder, it is not to be condemned 
on that account ; for cement, little underburned or rather stale, is not. altogether 
unfit for use, as was proved by the experiments recorded in Article 12. Make a 
moist ball with it, and do not put it under water immediately, as you may do with 
well burned cement powder, fresh from the kiln ; but allow it to stand some hours 
before you immerse it, and the result will sufficiently test its fitness or unfitness 
for practical purposes. 
20. All gritty cement powder ought to be peremptorily rejected. But suppos- 
ing you are at a foreign station, and it has come out in this imperfect state from 
England, and you have no other alternative between receiving it and going without, 
I would recommend sifting it with a very fine sieve, and pounding the coarser 
parts, previously to use. 8 
,. ne of ce '" e " t ^der being reduced to the most minute state of 
division possible may easily be proved thus :-Take a small quantity of common 
Harwich cement from the cask, which is usually gritty, and make it up into a moist 
ball with water. Pound an equal quantity of the same in a common mortar, until 
you reduce it to an impalpable powder- and *■, . * 
L, , I, 7 P > and another moist ball with th s. 
Ihe finely pounded cement hall will • i 
more heat • and will bo • , c 1 9 uic ker than the other, and with 
more heat , and will be close grained and hard ; whilst the other will remain soft 
and porous, and will imbibe a great ouantinr , , *- , . . 111 iemaln h0 
. * * _ « great quantity of water on being immersed • and will 
give out a soft matter like mo st clav, on beino- r„i u i i ’ 
Dei ng rubbed when wet ao-ainsf tbo hark 
o the band. Moreover, the finely pounded cement will adhere to the surface of dry 
brick work, from which the coarse cement will be liable to detach itself. 
1 I have no reason to suppose, that this nraot;,.,. -i , , 
earliest cement manufacturers in this country Led toLnT. 7' T™!’ aU,, °”“ 
hut also casks of stucco, consisting of the cement 7 J ""'^asks of P ure cel " en,; 
ing, of course, different prices. The sale of s 7 f" "" Xed W " b M " d ’ a " d ^ 
ought to be no silicious sand in a cask of cement. h ‘”' 1 " S: become ob “lete, then 
