HILLEBEAND.] BORON, NITROGEN. 107 
XXV. BORON. 
To the best of the writer's belief, it has never been found necessary 
in this laboratory to estimate boron in a silicate rock. Should the 
determination be required, since most silico-borates are insoluble min- 
erals, it would probably be necessary to fuse with sodium carbonate, 
extract with water, faintly acidify with nitric or acetic acid, expel the 
boron by distillation with methyl alcohol, and collect the boric ether 
in a suitable manner. For simple borates, artificial or native, this 
method, 1 first devised by Rosenbladt and Gooch independently, gives 
entire satisfaction when all needful precautions arc carefully observed, 
but its application to boro-silicates yet needs investigation, in view of 
the as yet unexplained very discordant results obtained some years 
ago by J. E. Whitfield in this laboratory on the mineral warwickite, :i 
boro-titanate of magnesium and iron. 
It is also quite possible that the accurate estimation of but a few 
milligrams or even less of boric oxide by the use of a large excess of 
lime as a retainer would not be feasible. Fluorine would have to be 
first removed by calcium nitrate or acetate before freeing the boron. 
XXVI. NITROGEN. 
Nitrogen has been found in igneous rocks or the minerals occurring 
in them by several observers. Thus, H. Rose 2 says that pitchstone 
gives off ammoniacal water on heating; Silvestri 3 mentions a nitride 
of iron in lavas from Etna; Sandberger finds ammonium carbonate to 
be given off from certain rocks of Pribram; the writer has shown 
nitrogen to exist in u rani nit e; Ramsay and others have noted it in 
traces with or without helium, etc., in numerous minerals; and later 
Erdmann 4 found it to be given off as ammonia on treating various 
minerals of "ancient igneous rocks" with a caustic alkali. Luedeking 
also found ammonium sulphate in a barite from Missouri, the presence 
of which the writer was able to confirm. 
It has been noted in this laboratory on three separate occasions, when 
series of ores, roofing slates, and eruptive rocks were analyzed, that 
1 Rosenbladt (Zeitschr. fur anal. Chemie, Vol. XXVI, p. 21, 1887) used magnesia for binding the boron, 
while Gooch (Proe. Am. Acad. Arts and Sci., p. 167, 1886; Hull. V. S. Geol. Survey No. 42, p. 64; Chem- 
ical News, Vol. LV, p. 7, 1887) preferred lime, as more active and reliable. Gooch and Jones have 
later (Am. Journ. Sci., 4th series, Vol. VII, p. 34, 1899; Chemical News, Vol. LXXIX, pp. 99, 111, L899) 
upheld the use of lime and proposed, as a, convenient though perhaps not quite so perfeel substitute, 
sodium tungstate containing an excess of tungstic oxide. In this article they likewise indicate the 
precautions now used to insure complete collection and retention of the boron. 
For a useful modification in the way of collecting the boric ether in ammonia before bringing in 
contact with the lime, see Penfield and Sperry i Am. Journ. Sci., 3d series, Vol. X X X i V. p. 222, L887); 
also Moissan (Comptes Renducs, Vol. CXVI. p. L087, L893, and Bull. Soc. Chim., Vol. XII, p. 955, L894), 
who modi iii- the Gooch distilling apparatus in certain respects. 
2Quantitative Analyse, p. (17:;. Finkeiier edition. 
SGazz. chim. ital.. Vol. V, p. 803, 1875. 
iBer. Deutscb. chem. Gesell.. Vol. XXIX. p. 1710, 1896. 
