676 THURAS: RECORDING SEA- WATER SALINITY 



Since the spinels are regarded as alferric minerals, the rock 

 falls in Class III, Subclass V, and in Section I of the C. I. W. P. 

 system. 



THE NAME SPINELLITE 



The name spinellite, applied by Peterssen and Sjogren^ in 

 1893 to the titaniferous iron ore at Routivare in northern Swe- 

 den composed of the ore minerals magnetite, ilmenite, and 

 spinel with the silicate minerals olivine and pyroxene, seems 

 applicable to the Virginia rock. Indeed the name seems more 

 applicable, since the chief mineral in the Virginia rock is spinel. 

 Based on the group name spinel, spinellite would have equal ap- 

 plication to the two rocks, since magnetite and spinel compre- 

 hended under it are important constituents but their ratio in 

 the two rocks is reversed. 



Since 1893 occurrences of titanomagnetite-spinellite in Nor- 

 way and Sw^eden have been found to be rather frequent. They 

 are grouped as magmatic segregation deposits in chiefly gabbroic 

 rocks and generally contain 7 to 12 per cent of spinel,^ but as a 

 rule, carry no corundum, which latter is an important mineral in 

 the Virginia rock. Based, then, on mineral composition, the 

 Virginia rock in which spinel is the principal component is re- 

 ferred to spinellite, which would also include the Peekskill, New 

 York, occurrence. 



OCEANOGRAPHY. — An instrument for recording sea-ivater 

 salinity.^ A. L. Thuras, Bureau of Standards. (Com- 

 municated by S. W. Stratton.) 



In a paper pubhshed in this Journal, 8: 145. 1918, a de- 

 scription w^as given of an instrument for continuously recording 

 sea-w^ater salinity. This instrument has been constructed and 

 tested and experimental data have been obtained giving the 

 magnitude of the various sources of error. The present paper 



« Zeitschr. prakt. Geol., p. 269, 1893; Geol. Foren. Forh. 1893. 



^ Beyschlag, Vogt, and Krusch., Ore Deposits, 1: 250 et seq. (Trans, by 

 Truscott.) 1914. 



1 Done under the auspices of the Interdepartmental Committee on Ocean- 

 ography, subcommittee on instruments, apparatus, and measurements. 



