PREFACE. 



The following Report has been prepared under the 

 direction and at the expense of the Smithsonian Insti- 

 tution, from articles in various Journals of Science and 

 the Arts, published during the last few years, in the 

 English, French, and German languages; and, among 

 these, we acknowledge our indebtedness chiefly to the 

 Chemical Gazette, issued in London, and to the excel- 

 lent Report on Practical Chemistry, by Dr. Eisner, of 

 Berlin. We have freely exercised discrimination in the 

 selection of subjects, and have omitted much that we 

 found on Applied Chemistry, because novel views need 

 in many cases further confirmation to render them re- 

 liable in practice, and, if presented too early to the ar- 

 tisan, may be productive of more evil than good. We 

 have kept in view the benefit of the practical man, the 

 manufacturer or maker, and, while we have not avoided 

 scientific terms when more convenient, we have gene- 

 rally used modes of description intelligible to every one. 



American Patents relating to the Chemical Arts 

 have been generally omitted, because they are published 

 annually in the Reports of the Patent Office, which 

 are widely distributed throughout the United States, 

 and therefore accessible to all. 



