THE TROPICAL AGRICULTURIST. [August i, 1888. 
96 
A CEYLON PLANTER'S EXPERIENCE IN 
PERAK. 
The following extract from a private letter of Mr. 
A. L. Ingall, now settled down to planting work iu 
Prrak, is very interesting. His old friends in Ceylon 
will be glad to hear he is fit and well, and very en- 
thusiastic as to the vigor of the Arabian coffee in 
Perak, which appears to have astonished him and 
reminded him of the old days when the palam used 
to come in renduc-rendue-bushel fashion. He says : — 
The climate is not good, but it is not particularly bad, 
and the temperature is wonderfully low. The place 
I am opening is only 400 feet above sea level, and is 
really very little hotter than Kandy, while the bungalow 
on Elphinstone's place (1,700 feet) is very like the 
lower end of Dikoya. The coffee on Waterloo (Elphin- 
stone's place) is looking simply splendid, and had a 
good blossom out which set well. It makes me wish 
I had a few dollars to open up Arabian coffee. The 
country to look at, is very much like Ceylon: loug 
tracts of low land rising up to the hills, though very 
little of it is cultivated, the Malays being essentially 
lazy — not at all like those we were accustomed to 
tee in Ceylon. I had tremendously hard work to 
get men to fell, but succeeded in getting a mixed 
force of Chinese, Malays, and Sakeis; the latter are 
the wild men of Perak, and have wonderfully scanty 
clothing. They roam about and never settle for more 
than a year in any one place, eat roots mostly, and 
are entirely uncivilized, but very pleasant and goad- 
tempered people. Their hair is curly like a negro's, 
and their only weapon a blow pipe with poisoned 
arrows and a club.— Local ''Times." 
+ 
THE EFFECT OF SEA WATER ON PORTLAND 
CEMENT.* 
By Henry Faita, M.Inst.O.E. 
The subject of the paper which the author has 
the honour of reading before the Society this even- 
ing is suggested by the reports which have been 
made public of certain failures of concrete work 
at Aberdeen: the failurea being attributed to the 
ohemical action of the sea on Portland cement. 
The author would like to call attention to this 
question of magnesia iu cement, which has also 
lately disturbed the equanimity of users of cement, 
and he wishes more particularly to make it clearly 
understood that magnesia in cement — i.e., incorpor- 
ated iu it in the course of manufacture, through 
the use of improper and unsuitable raw material,— 
is in a very different form to the magnesia pre- 
cipitated from the sea water. 
Magnesia incorporated iu a cement is in a state 
similar to caustic or quicklime, and on the addition 
of water, acts in a similar manner, i.e., it heats and 
expands with considerable force; and if, therefore, 
it exists in any considerable quantity, it will cause 
the cement to "blow" or expand, and destroy the 
structure of which it forms a part. The explanation 
of this is brit-Hy that the temperature at which a 
cement is burned is sufficient only to cause a perfect 
chemical combination between the lime, silica, alumi- 
na and a part only of any magnesium carbonate 
which may exist in the raw materials ; the remain- 
der is only doprived of its carbonic acid by the 
calcination, and is left in the cement as free or 
caustic magnesia. Cement may be made, and the 
author has made by heavy burning cement contain- 
ing as much as 5 per cent, of maguesia, which w;is 
perfectly sound, but he is of opinion that 3 per 
cent, should be considered the limit of safety. It 
need scarcely be added that 5 or 6 per cent, of 
free or caustic lime in a cement would be just as 
dingerous as the same percentage of magnesia. The 
magnesia iu the sea exists piincipally in the form 
of magnesium chloride, and is precipitated as hydrate, 
and in this form it is perfectly inert ; in fact, 
* A Paper road before the Society of Engineers on 
March 5th 1888. 
t is to continue the comparison, similar 1o a slack 
Hme, and has no power of expansion. That it is 
found by analysis in cement which lias been im- 
me rsed in the sea there is no question, but the 
author maintains that it simply fills the pores or 
interstices of the concrete, without in any way 
combining with and forming a comt^tuent part of 
the cement. 
The foregoing, though apparently a digression, is 
really of very great importance, because it shows a 
continuity of thought — from the effects or magnesia 
in cement, to the effect of sea water on cement, — 
and suggests that the latter is considered us the 
corollary of the former; in the author'6 opinion 
iocorrectly, for the magnesia in the two cases is in 
such very different forms that they are in no way 
analogous. Referring first, to Professor Brazier's 
analysis and experiments, he first analysed three 
samples of the original cement, in the form of 
broken briquettes, and also one sample of the cem- 
ent in powder. In none of these did he find so 
much as 1 per cent, of magnesia. Analyses of several 
samples of the "decomposed cement" from the 
graving-dock were then made, and in them the hy- 
drate of maguesia varied from 13 to 21 per cent.; 
at the same time, the lime had decreased fiom 58 - 49 
per ceut. in the original sample to about 33 per 
cent, of carbonate and hydrate combined ; he there- 
fore inferred that some of the lime of the cement 
was dissolved, and some of the magnesia contained 
iu the sea water precipitated. To satisfy himself 
on this point, Professor Brazier made the following 
laboratory experiment. Some of the cement in its 
original form of powder, which contained practically 
no magnesia, was digested in a pint of sea-water 
for four days ; the analysis of the water and cement 
were made before and after, with the result) that 
at the end of the four days, the water was found 
to have gained 28T6 grains of lime, and to have 
lost 12-52 grains of maguesia. The argument seenus 
conclusive, but the author thinks it is at fault, in- 
somuch that, to keep the cement digesting is to 
keep it on the move, and therefore to prevent it 
lrom setting. It is well known that cement will 
set freely if left alone in sea-water, and it seems 
reasonable to suppose that if the cement sets, dis- 
integration, except from some cause within the cement 
itself, is impossible; aud that if the disintegration 
of the cement takes place through the unsound nature 
of the cement, then the lime in it would be parti- 
ally dissolved, aud the maguesia iu the sea-water 
precipitated. The author is, therefore, of opinion, 
that the cause of the failures of the concrete at 
Aberdeen is not to be looked for in the chemical 
action of the sea on a properly set Portland cement, 
but that they are due to the cement having never 
been properly set, or that the cement used was an 
unsound one, and disintegrated from causes within 
itself. — Indian Engineer. 
+ 
Manila Hemp. — The Belgian Bulletin du Mus£e 
Commercial- for May 19th, quoting from the Deutsche* 
Hand 'els- Arc hiv, gives some particulars regarding [I 
the trade in Manila hemp in the Philippine Islands. 
Besides its employment for ropes and cordage, ex- 
periments have lately been made to utilise Manila 
hemp for other purposes. At Madrid last year an 
attempt was started to make paper out of the waste 
fibre. It is said that an excellent white paper was 
produced, without the aid of any other material. I 
If this experiment should be repeated with success, 
a fresh impetus will doubtless be given to the 
cultivation of the abaca, It should be understood , 
that the waste fihre is not useless, even at present ; : 
it is employed to manure the plantations. The 
great export of hemp is from Manila and from Cebu 
some is also sent from the port of Iloilo. — L.&C. 
Express, June 22nd. 
