I. SPECIAL COLLECTIONS. 129 



i 



SECTION 5. MOLECULAR PHYSICS. 



WEST GALLERY, UPPER FLOOR ROOM ( Q). 



I. SPECIAL COLLECTIONS. 



STANDARDS OP THE HYDROMETERS AND THERMOMETERS USED 

 BY GOVERNMENT OFFICERS IN HOLLAND. 



Exhibited by Dr. J. W. Gunning, Professor of Chemistry at the 

 " Athcnceum illustre" Amsterdam. 



579. General Hydrometer (No. 1), with open stem and 

 variable weight. Every degree has a bulb equal to yiy of the part 

 of the hydrometer below zero. When this instrument, having the 

 arbitrary weight = W, marks a degrees in a liquid, the apparent 

 specific gravity of that liquid at the observed temperature will 



: (100 + ) 1,014,608. 



580. Instruments (Nos. 2 and 3) for ascertaining the strength 

 of alcoholic liquors. The degrees are the same as in No. 1, but the 

 weight is not variable, and the zero is the immersion point at 

 15 C. in a liquid, of which the specific gravity at that temperature 

 is equal to the specific gravity of pure water at 4 C. Tables are 

 added, those of Professor von Baumhanrr (1863), used in Holland ; 

 those of the exhibitor (1873), used in the colonies. The latter are 

 based on the researches of Mendelejeff. Philos. Mag. (4) XXIX. 

 395.) 



581. Hydrometer (No. 4), for liquids of a specific gravity 

 greater than 1. The construction is the same as in Nos. 2 and 3. 

 The Beaume scale is added. Used for solutions of salts and sugar 

 juices. 



582. Hydrometers (Nos. 5 and 6), for ascertaining the 

 specific gravity of seed oils and of petrol, allowing immediate 

 application of correction for temperatures, other than 15C. (For 

 description see Scheik. Bijdragen door J. W. Gunning, Amster- 

 dam, 1867.31.) 



583. Densimeters (Nos. 7, 8, and 9), with flat stems. The 

 zero is the same as in Nos. 2 and 3. 



3&508. I 



