Scientific Intelligence. 207 
It is universally known, that the acids, either single or combined, 
in different degrees, are the agents, employed in producing these 
beautiful effects upon tinned iron. 
The following mixtures may be employed with perfect success, 
upon tin plate gently heated. 
1. Four parts of nitric acid, one of muriate of soda or of muriate 
of ammonia, two of distilled water. 
2. Two parts of nitric acid, one of muriatic acid, and from two to 
four parts of distilled water. 
3. One part of nitric acid, two of muriatic acid, three of distilled 
water. 
4. 'Two parts of nitric acid, two of muriatic acid, two of distilled 
water, and two of sulphuric acid. 
Process.—Kither of the above mixtures being placed in a common 
glass, a sponge is wet with the fluid, and immediately applied to the 
tin plate, until it is every where equally moistened. If the plate has 
been slightly heated, or the acid has been but little diluted, the pecul- 
iar configuration, (moiré,) is produced i in less than a minute, other- 
Wise it will require from five to ‘ten minutes. Afterwards the plate 
is wet with cold water, and washed by rubbing it gently with a piece of 
Cotton, or with the plume of a quill, but by no means with the hand; 
it is then left to dry. Itis never proper to pour the acid upon the 
plate, because this will produce great black spots where it falls ; fre- 
quently one part will be oxidized before the other parts are 
crystallized, because the acid is not every where equally diffused at the 
same moment. Oxidation takes place also, if the plate after washing 
be dried too near the fire, and, as the same effect will happen from 
the gradual action of the air, it is necessary to varnish the work.* 
What is called le moiré forcé, is produced by bringing the tin plate 
into contact with red hot iron, and then applying the acids to the op- 
posite side. Stars and other very beautiful designs are made by 
bringing i into contact with the tin plate, the flame of an enameller’s 
lamp, but with so much caution as to be sure that the tin is not melted. 
Although these operations appear to be easy, it is impossible to 
succeed well without acquiring a certain tact by practice. 
The washing is the most i tthing. An instant, more or less, 
alters the effect entirely. If the process be stopped too soon, there 
is no beauty or lustre, if not soon enough, the peer a —— 
* By employing a and transparent varnishes, the beauty of the work is 
greatly inereased.— : 
