1829.] 
On the Chinese Lacker. 
337 
From these and the classification of such data throughout the register, the follow- 
ing table was framed. 
1 '■*-< 
<u o . 
a. qj .s 
ri n w 
Depression of the wet-bulb thermometer. 
07 as 
H £-2 
0° 
5° 
10° 
1 5° 
20° 
25° 
30° 
35° 
Tempe, 
60° 
0 
0,05 
0,11 
0,17 
0,23 



70 
0 
,07 
,13 
,20 
,27 
0,33 
— 
. 
80 
0 
,09 
,18 
,27 
,35 
0,53 
— 
90 
0 
1,2 
,25 
,37 
,50 
,63 
,75 
0,86 
Decimal parts of an inch evaporated 
in 24 hours. 
These numbers apply to small shallow surfaces of water sheltered fron the wind. 
It seems probable, that the wind on a large scale may more than compensate for 
increase of surface. The Vera Cruz average takes in the influence of wind, other- 
wise the climate of that place must be drier than Benares, which is very unlikely. 
The amount of evaporation is given by Dalton and others, in an inconvenient 
expression of “ the number of grains per minute for a given surface by converting 
these, however, into similar terms, we have the following contrast, at a wet bulb 
depression of 20 degrees. 
Temperature. Aqueous Tension 
centesimal. 
60 0 
70 10 
80 20 
90 30 
Whence it appears that the actual evaporation daily from a set of four years ex- 
periments, turns out little more than one half the quantity given by Dalton's formula. 
We have, ourselves, made some direct experiments on the subject, which, as far as 
they go, confirm the above curious result. 
Evaporation Evaporation 
by Dalton, by above table. 
0,23 
0,27 
0,35 
0,50 
0,42 
0,52 
0,65 
0,76 
Ratio. 
1,8 
1,8 
1,8 
1,5 
X. — On the Chinese Lacker. 
In our 6tli No. we published the contents of a letter from a gentleman in Calcutta, 
to a friend in China, containing enquiries regarding the nature of the Chinese Lacker, 
and a suggestion, whether it might not be the same as the Burmese varnish, of which 
a specimen was sent for the purpose of trial and comparison. The reply which was 
also published in that number, was not so full or satisfactory as coulll have been 
wished ; and indeed the most interesting and important of the queries, the identity of 
the two substances, was left altogether unnoticed. The following letter, which has 
been recently received, in a great measure supplies these deficiencies ; and we think 
will be read with interest. We wish however, we could print the specimens sent 
by the writer of the letter, as they throw more light on the subject than can any de- 
scription. The inferior sort or No. 1, of the Chinese lacker, was, we thought, a little 
better than the Burmese, but very little ; the others decidedly so ; but the best or No. 
5, was exceedingly beautiful, and its lustre can only be compared to that of polished 
metal. The preparatory coating, of which also a specimen was sent, appeared to us 
very similar to the size coating given by painters to carriages before laying on the 
proper colour. As far as these specimens go, they appear to us to decide the ques. 
tion in the negative, as to the identity of the two lackers ; hut whether justice has 
been doue the Burmese varnish is a question worth considering ; it is particularly to 
be adverted to, that the Chinese have five sorts, of which the worst is probably not 
much if at all better than the ordinary Burmese varnish. These five sorts are all 
drawn from the same tree, the only difference being the order iu which they are 
drawn, that taken first being best, and so on. It is possible that the Burmese may 
not be aware of this circumstance, and it might be worth enquiry to ascertain whe- 
ther there be any difference in the quality according to its priority of flowing. This 
point may be even worthy of attention, though the specimen of the tree which is 
premised in the letter should prove that the two are not the same, inasmuch as it 
might occasion the same improvement of the Burmese varnish, as it has evidently 
of the Chinese. 
