The following process is so plain and easy of trial that any Daguerreotypist can try it.

This is as given by Mr.James Campbell, and was published in Humphrey's Journal of the Daguerreotype and Photographic Arts, vol.5, page 11.

Mr.Campbell has done much to further the process announced by M.Neipce, and his experiments have proved highly successful.
The following is submitted as worthy of trial: "The proper preparation of the chloridated plate, to enable it to receive colored impressions is an object of the first importance to those wishing to experiment on it, and consequently requires particular notice.

The plate may be prepared by making it the positive pole of a battery, and letting it at the same time be immersed in chlorine water.
The negative pole should be a slip of platinum.

All the colors may be produced from a plate so prepared if the chlorine and water are in the right proportions; but generally one color or the other predominates, according to the amount of chlorine in the liquid.