346 
Notice to Correspondents . 
gress. But circumstances have obliged me to defer the full exe- 
cution of the task to a more propitious moment. I remain, &c. 
Thomas Coo/ier , Esq. Carlisle. E. BOLLMAN. 
Upon this letter I have to remark; 
That I am well aware of the fact, that the specific gravity of 
metals is encreased by hammering : but I doubt whether ham- 
mering alone will bring platina from 19,5 to 23, though I know 
that mercury is encreased by congelation from 13,5 to 15,6. 
I have not ventured to say that the process I describe, is the 
same with Dr. Bollman’s. I understand it to be the process hitherto 
commonly used in France and England. Achard’s method with ar- 
senic I have tried ; but heat alone will not drive off the arsenic. 
Whenever Dr. Bollman finds it convenient to publish his process, 
I shall be very glad to make the Emporium the mean of commu- 
nication. 
I have said, manufacturers are secret-mongers. They are so ; 
and they have a right to be so, if they think fit. I know of no ob- 
ligation that calls upon them to disclose those secrets upon which 
their subsistence may depend. When they conceal, and make se- 
crets of the common and usual processes of their manufacture, they 
do not act liberally : when they conceal processes peculiar to them- 
selves, or not generally known, they exercise a caution, which may 
frequently be a duty. It is no term of reproach. The public are 
obliged to those who communicate knowledge of any kind ; and 
every man who has lived long, and much in the world, and who 
has observed much, has much to communicate that the public 
will be the Aviser for knotving ; but there is no obligation on him to 
do so. 
Dr. Bollman is fearful Jest the Avags should say he has turned 
spoon-maker. What! Avas not Prince Rupert a manufacturer — - 
the Marquis of Worcester an engineer — the Duke of Bridgewater 
a canal-digger — the Duke of Norfolk and Lord Dundonnaid manu- 
facturers of coak and coal tar ? Was not Sir Richard Arkwright 
a cotton spinner — Wedgwood and Bentley, potters ? Are not Boul- 
ton and Watt spoon-makers? Does not Dr. Wollaston manufac- 
ture platina spoons? Tell me the men of Europe of whom their 
country has more reason to be proud, than Watt and Boulton and 
Wollaston ? Lord Loughborough was right, Avlien he said in de- 
bate, that Aveighed in the balances against such men as Boulton and 
Watt, Sir Richard Arkwright, the duke of Bridgewater and W edge- 
wood and Bentley, the Lords and the Commons Avould kick the 
beam. Dr. Bollman need not be ashamed of company in all re- 
spects so truly honourable. I should be glad to have discovered, 
as Dr. Bollman appears to have done, a method of manufacturing 
platina easily and cheaply into spoons or any other article of use or 
ornament, from the boiler of a steam engine to the spoon of a gal- 
vanic, or the crucible of an analytical chemist. 
Dr. Bollman differs from me, in my notions of political economy : 
I am glad of it. I shall have an antagonist worth contending Avith. 
Whenever Dr. Bollman will send me his communications on this 
or any other subject, they shall be treated with the attention his 
talents have a right to claim. T. C. 
