PREFACE 



Excepting the preliminary calibration of the dipping refractom- 

 eter to measure the salinity of sea water and of boiler water, this 

 publication merely studies methods already available. Such slight 

 modifications have been made in these methods as seemed to make 

 them best suited to the hydrographic work of the Coast and Geo- 

 detic Survey. 



Concerning the manipulation of the hydrometer at sea, valuable 

 suggestions were received from reports on its use in the echo -sound- 

 ing work of the Coast and Geodetic Survey ship Surveyor. 



In connection with the titration method, valuable help was given 

 by Roger C. Wells, of the United States Geological Survey, and by 

 J. W. Sale, of the Food, Drugs, and Insecticides Administration. 

 Through the courtesy of Mr. Sale, the samples used in the prelimi- 

 nary refractometer calibration were standardized, both by pycnom- 

 eter and by chlorine titration, by the latter organization. For 

 the excellent photograph of the refractometer the author is indebted 

 to the manufacturers, the Bausch & Lomb Optical Co. 



For information concerning the electrical conductivity method the 

 author is indebted to Dr. Frank Wenner, of the Bureau of Stand- 

 ards, and to Dr. G. Gueben, of the University of Liege. 



The sinker method described by Mr. Cummings and used at the 

 Scripps Institution of Oceanography was made known to the writer 

 by Dr. George F. McEwen of that institution. 



The tests made, and the present resultant publication, were made 

 possible largely by the interest and encouragement of W. E. Parker, 

 chief of the division of hydrography and topography of the Coast 

 and Geodetic Survey, and K. T. Adams, commanding officer of the 

 survey ship Lydonia. Thanks are also due the many other mem- 

 bers of this bureau who cooperated in the work. 



