A MANUAL
OF
PHOTOGRAPHIC CHEMISTRY.
A MANUAL
OF
PHOTOGRAPHIC CHEMISTRY,
INCLUDING THE
PRACTICE OF THE COLLODION PROCESS.
By
T. FREDERICK HARDWICH,
LECTURER ON PHOTOGRAPHY IN KING'S COLLEGE, LONDON;
LATE DEMONSTRATOR OF CHEMISTRY IN KING'S COLLEGE.
Fourth Edition.
LONDON:
JOHN CHURCHILL, NEW BURLINGTON STREET.
MDCCCLVII.
[The Author reserves to himself the right of translating this Edition.]
PRINTED BY
JOHN EDWARD TAYLOR, LITTLE QUEEN STREET,
LINCOLN'S INN FIELDS.
PREFACE TO THE THIRD EDITION.
It is a source of much, gratification to the Author to findhimself called upon to prepare a Third Edition of hisManual in less than fourteen months from the date of itsfirst publication. No greater proof could have been affordedof the rapid advance which the Photographic Artis now making in this country.
On once more entering upon the task of revision, theWriter has been led to reflect in what way the utility ofthe Work may be promoted; and from numerous inquirieshe believes that this result will best be attained by carefullyomitting everything which does not possess practicalas well as scientific interest. The majority of Photographerslook to the Art to furnish them with amusement aswell as instruction, and they are deterred from enteringupon a study which seems to involve a great amount oftechnical detail: these remarks however are not intendedto discourage a habit of perseverance and careful observation,but simply to distinguish between the essential andthe non-essential in the theory of the subject.
The present Edition differs in many important particularsfrom those which have preceded it. It has undergonea fresh arrangement throughout. In some parts it is condensed,in others enlarged. The Chapters on PhotographicPrinting are entirely re-written, and include the whole[vi]of the Author's investigations, as published in the Society'sJournal. The minute directions given in this part of theWork will show how much success in Photography isthought to depend upon a careful attention to minor particulars.
Another point which has been kept in view, is to recommend,as far as possible, the employment of chemicalagents which are used in medicine and vended by alldruggists throughout the united kingdom. It is often anadvantage to the Amateur to be able to purchase his materialsnear at hand; and, if the commo