62 BUREAU OF AMERICAN ETHNOLOGY [BULL. -36 
loss in weight recorded as volatile matter; this comprises firmly 
combined water, carbon dioxide, and organic substances. 
&quot; The sample was then dissolved in dilute nitric acid, and the solu 
tion filtered, the residue being ignited and weighed and examined 
microscopically. In every case it proved to be made up of quartz- 
sand and clay ; and, as such material is clearly a mechanical admix 
ture with the bone, it was deducted in each case from the total weight 
of sample taken, so that the percentages of material calculated would 
represent material combined in the bone substance and the results on 
the several samples would be directly comparable. 
&quot; The nitric acid solution was heated to boiling, made slightly alka 
line with ammonia a small amount of mixed phosphates being 
thereby precipitated and an excess of acetic acid was added. Cal 
cium phosphate then went completely into solution, while the phos 
phates of aluminium and iron remained insoluble, and were filtered 
out, ignited, and weighed. The amount of iron was so small that it 
was not separately determined. When the precipitate was large in 
amount it was fused with sodium carbonate, dissolved in nitric acid, 
and the phosphate removed by ammonium molybdate, and deter 
mined as magnesium pyrophosphate; the phosphoric oxide found 
was deducted from the total precipitate, and the remainder recorded 
as A1 2 O 3 (+Fe 2 O 3 ). When the amount of precipitate was small, 
the phosphoric oxide in it was calculated on the basis of the com 
pound A1PO 4 and subtracted as before. 
&quot; The acetic acid solution, from which aluminium had been re 
moved, was diluted to a definite volume and divided into two equal 
parts. To one part ammonium oxalate was added and the calcium 
oxalate precipitated was filtered out, -ignited, and weighed as Ca(). 
To the filtrate from this ammonia was added and the magnesium- 
ammonium phosphate precipitated was ignited arid weighed as the 
pyrophosphate, from which the MgO was calculated. Phosphoric 
oxide was determined in the remaining half of the acetic acid solu 
tion by titration with a standard solution of uranium acetate; 
the amount in the aluminium precipitate being added to give the 
total P 2 O 5 . 
&quot; For the determination of fluorine a fresh sample weighing 0.4 
gram was dried, mixed with pulverized quartz, and heated to 200 
with specially concentrated sulphuric acid in a stream of dry air, 
acid fumes carried over being removed by filtering the air through 
dry asbestos, and the gases being collected by bubbling through water. 
The hydrogen fluoride dissolved in the water was titrated with stand 
ard sodium hydroxide solution, and the percentage of fluorine present 
in the bone thus obtained. 
&quot; The specific gravities were determined on the powdered bone, 
using the picnometer, at about 20. 
