ON THE CRYSTALLINE SLAGS. 363 
some of the powder of the slag and hydrochloric acid, blackening was slowly 
produced. No quantitative determination of sulphur was made. 
10. Phosphoric acid. The precipitate obtained by ammonia (8 in the 
potass examination) was dissolved in hydrochloric acid, tartaric acid was 
added, and then excess of ammonia, and finally chloride of magnesium. After 
standing many days not a trace of crystalline precipitate could be detected. 
9. Anatysis &. By J. P. 
1. Weight of slag 20°21 grains. Fused with 100 grains of the carbonate 
_ of potass-soda mixture. 
2. Silica 10°81. 
3. Alumina 1°05. 
4. Sulphate of lime 14°97. 
5. Phosphate of magnesia 5°26. 
6. Sesquioxide of iron 0°20. 
Analysis tabulated. a. b. Mean. Oxygen. 
|S) CCE Ya A A er 8 BROT Me. | DRAB eben OO AL coin cele cie le 
Alumina............ 506 .. 519... Ir) AA ee 2°81 
Oy) Ua Se BR Rr 3065 .. 30°78 .. 30°71 .. 8°62 
Magnesia’ ..........- aT ts. feo, dint. 9 OG? . selon 
Protoxide of manganese 1°41 .. iB AS TA ok 0°31 
Protoxide of iron .... 1°02 .. Oso .. O95 .. 0:21 
101:06 
10. Anatysis. By D. F. 
1. Weight of slag 17:54 grains. Fused with 80 grains of the carbonate of 
potass-soda mixture. : 
2. Silica 9°43. 
_ 3. Alumina 0°84. 
4, Sulphate of lime 12°43. 
5. Phosphate of magnesia 4°70. 
6. Oxide of manganese 0-24. 
_ 7. Sesquioxide of iron 0°29. 
8. Potass. The slag was decomposed by digestion with fluoride of calcium 
nd sulphuric acid. Potass was not detected. 
Analysis tabulated. Oxygen. 
Silica: is DP ad oe e's SRT RG eae 27°93 
Adem as ob. 5» 5%, 2 AcE Wiehe s\alate 2:29 
Line. 2 sop eae Ws «) o!olalg 29°48 ss eee 8:28 
Magnesia: ictas 2.3: O82) ne args) ) O80, 
Protoxide of manganese .. 1°30 ...... 0°29 
Protoxide of iron........ TAB Oise OBE 
100°60 
ith the exception of a few small crystals in a drusy cavity in No. 9, the 
rystallization of the two preceding slags is confused, so that we could scarcely 
ope to deduce from their composition a satisfactory formula. The oxygen 
the acid being nearly double that of the bases, the slag is formed of bisili- 
and evidently approximates very nearly in composition to some varieties 
ugite (pyroxene) containing alumina. Several analyses of augite giving 
yout the same per-centage of alumina may be found in the first part of 
2B2 
