e., 0.096 per cent, by
volume, or 0.102 per cent, by volume of H_2S; but the phosphorus showed
the low figure of 0.36 milligramme per litre (0.031 per cent, of P or
0.034 per cent, of PH_3 by volume).
The British Acetylene Association's regulations relating to carbide of
calcium (_vide_ Chap. XIV.) contain a clause to the effect that
"carbide which, when properly decomposed, yields acetylene containing
from all phosphorus compounds therein more than 0.05 per cent, by volume
of phosphoretted hydrogen, may be refused by the buyer." This limit is
equivalent to 0.74 milligramme of phosphorus calculated as PH_3 per
litre. A latitude of 0.01 per cent, is, however, allowed for the
analysis, so that the ultimate limit on which carbide could be rejected
is: 0.06 volume per cent. of PH_3, or 0.89 milligramme of phosphorus per
litre.
The existence in appreciable quantity of combined silicon as a normal
impurity in acetylene seems still open to doubt. Calcium carbide
frequently contains notable quantities of iron and other silicides; but
although these bodies are decomposed by acids, yielding hydrogen
silicide, or siliciuretted hydrogen, they are not attacked by plain
water.
Pages:
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341