The manner in which the ISTew York state museum bulletin no. 

 12, entitled Clay industries of New York, was received by 

 the public, indicated that the subject was of interest to a large 

 number of persona and it therefore seemed important, as soon as 

 the means were available, to thoroughly revise this bulletin and 

 bring it up to date so as to cover the great progre^ made in this 

 manufacturing industry, Dr Heinrich Ries has accordingly devoted 

 himself to this work of revision and after much careful labor has 

 produced the work now submitted to the public. The chapter on 

 the physical properties of clay should be of particular value, since 

 Dr Ries has made a special visit tO' Berlin for the purpose of in- 

 vestigating this subject in relation to^ the clays of Europe. 



Fkedeeiok J. H. Merrill 



New Yorh state museum Director. 



Albany N. Y. 

 1899 



