83 
CEYLON MANUAL OF CHEMI- 
CAL ANALYSES. 
A HANDBOOK OF ANALYSES CONNECTED WITH 
THE INDUSTRIES AND PUBLIC HEALTH OF 
CEYLON FOE PLANTERS, COMMERCIAL MEN, 
AGRICULTURAL STUDENTS, AND MEMBERS OF 
LOCAL BOARDS. 
By M. COCHRAN, m.a., f.cs., 
(Continued from page \2.J 
CHAPTER XIV. 
CLAYS, CEMENTS, HYDRAULIC MORTARS, 
CONCRETES, PLUMBAGO. 
Ceylon kaolin and other china clays — 
ceylon brick clay— various kinds of clay 
— ceylon clay used for manufacture 
of hydraulic cement — portland cement — 
hydraulic limes and mortars— concretes 
various— decay of cement — influence of 
magnesia on quality of cement— plumbago 
—its varieties— analyses of ceylon plum- 
bago dust — tables of analyses of plum- 
bagos of various countries— canadian and 
ceylon graphites — proportionate amounts 
of graphite used for differert purposes 
in the arts. 
Kaolin or China Clay. 
The following is the analysis of a sample of 
China clay from a railway cutting at Bernwala. 
( 'onsidering that the clay had not been subjected 
to the process of levigation or washing, its com- 
position compares well with that of superior 
qualities of washed China clay as will be seen 
in the accompanying table : — 
02 
oo -* r-i I f3 (ji c-1 
7 « 
O o ^ 
CO CO 
m cc 
55 
~ o a /. — 
03 
55 _2 cS 
m < O 3 .S pS ' i 
Besides being used in the manufacture of 
porcelain, China clay is also largely used in the 
manufacture of paper, aluminous cake sulphate of 
aluminum, alum and ultramarine. It is also used 
for the objectionable purpose of filling up the pores 
11 
of calico and adding weight to cotton fabrics. 
For the manufacture of salts of aluminum it 
is desirable to have a clay as free as possible 
from iron, as the alum used for some purposes, 
such as the manufacture of the finest writing 
papers, should not contain as much as - 001 per 
cent of iron. 
Beruwala day, it will be observed from the 
analysis, stands well in this respect of freedom 
from iron. 
Ceylon Brick Clay. 
The following two analyses exhibit the com- 
position of two samples, submitted to the author, 
of Ceylon clays used for the manufacture of 
ordinary bricks for building purposes. No. 1 is 
rather a siliceous clay, and No. 2 contains rather 
much oxide of iron. 
Analyses of two samples of Ceylon Brick Clay. 
Silica 
Alumina .. 
Oxide of iron 
Lime 
Magnesia ... 
Alkalies 
Organic matter 
No. 1. 
No 2. 
61-35 
54-14 
22-90 
25-64 
6-44 
10-03 
•92 
•78 
•19 
•33 
2-40 
1-32 
5-80 
7-84 
100-00 
100-00 
2:1 -80 
29-58 
Water in prepared clay 
The quality of brick clay may be regarded as 
superior according as its composition approximates 
to that of kaolin. 
The following are analyses executed in Richard- 
son's laboratory, and although somewhat incom- 
plete, the alkalies not having been determined, 
are sometimes quoted as types of the varieties 
of clay used in the arts. 
Analyses of various kinds of Clay. 
Stourbridge 
Pipe 
Sandy 
Blue 
Fire clay 
clay. 
clay. 
clay. 
Silica 
64-10 
53 66 
66-68 
46-38 
Alumina 
23-15 
32-00 
26 08 
38-04 
Oxide of iron.. 
1-85 
1 35 
1-26 
1-04 
Lime 
•40 
•84 
1-20 
Magnesia 
95 
trace 
trace 
trace 
Water 
10-00 
12-08 
514 
13-57 
100 05 
99-49 
100-00 
100 23 
I extract from the Ceylon Irrigation Board's 
Sessional Paper, 1891, an analysis of Ceylon clay 
regarded as suitable for the manufacture of 
hydraulic cement. 
The analysis is by Mr. Harold Slater, f.i.c, 
F.CS. 
per cent. 
Carbonic anhydride 
Organic matter 
Silica 
Alumina 
Iron oxide ... 
Sulphate of lime ... 
Sulphate of magnesia 
Alkalies 
trace 
10-76 
60-23 
14-41 
12-36 
•51 
•21 
1-52 
100-00 
Experiments are also detailed in the Sessional 
Paper referred to of cements locally manufactured 
from Ceylon clays. The best result obtained 
was from a mixture of 4 lb. slaked lime to 1 lb. 
clay, burnt for 4 hours. The briquette made in 
this manner shewed a tensile strength of 123 lbs. 
to the square inch. This cement may be useful for 
