FEBRUARY 22, 1901. ] 
trum of a black body as determined by Lummer 
and Pringsheim and by Kurlbaum. It is thus 
found that an atom of hydrogen weighs 1.64 < 
10 —* grams. Professor Planck compares this 
result, together with other results depending 
upon it, with previous approximate determina- 
tions of this quantity, and he remarks that the 
values determined by his formula are not ap- 
proximations, but that the calculations are ab- 
solutely valid, provided that his theory is true. 
W.S. F, 
NOTES ON INORGANIC CHEMISTRY. 
In an article by Berthelot in the Annales de 
Chimie et de Physique on Egyptian gold, it appears 
that in the earliest epochs, argentiferous alluvial 
gold was used for coins and other articles. Only 
later, from the time of Croesus down, was the 
gold refined. The period of manufacture can 
be approximately told by analysis, owing to 
the rarity of minerals which yield gold free 
from silver. Specimens of gold from the fifth 
and twelfth dynasties show about four per cent. 
of silver, but those from the Persian epoch 
consist of almost pure gold. 
In a recent number of the Chemical News, Dr. 
J. H. Gladstone gives an account of analyses 
made of specimens of gold leaf from Egyptian 
mummies, supplementing the work of Ber- 
thelot spoken of above. Down to the time 
of the eighteenth dynasty the foil is evidently 
made from the native alloy, containing from 
four to eighteen per cent. of silver, the lat- 
ter alloy closely approaching electrum. The 
specimens from the first dynasty show a simi- 
larity of composition, coming from a single 
source, but those from the later dynasties differ 
among themselves, and evidently had different 
origins. Little copper is found in any of the 
foils. A very thin superficial crust of chlorid 
of silver is found in some of the foil, indicating 
a slow diffusion of one part of the alloy—the 
silver—till it reaches the outside surface, where 
it meets with the chloride that exists in the 
sands of the desert. That the Egyptians 
were acquainted with different qualities of 
gold is evidenced by the Harris papyrus, 
containing the annals of Rameses III., about 
B. C. 1200, where mention is made of gold, 
pure gold, good gold, white gold, best gold, 
SCIENCE. 
315 
gold of the second quality, fine gold of the 
land, gold of the land of Koebti, and of 
Kush. 
THE recent cases of poisoning in England 
from arsenic contained in beer, and the differing 
results obtained by the chemists who have ana- 
lyzed the beer in question, have given rise to an 
extended discussion in the Chemical News and 
elsewhere, as to the value of the tests for arse- 
nic which are commonly relied upon to detect 
and estimate the amount of arsenic in suspected 
substances. This discussion is well timed, for, 
in the whole field of toxicology, no substance 
is more frequently to be tested for than arse- 
nic. The test most generally depended on is 
Marsh’s, and this is taught in almost every 
laboratory, of college and medical school. As 
a matter of fact, while this test is thoroughly 
reliable in the hands of a skilled analyst, it is 
beset with so many difficulties, which interfere 
with its accuracy, that it is of little value ex- 
cept when carried out by a chemist who has had 
long experience with it ; indeed in the hands of 
a neophyte it is often wholly misleading. This 
is well shown in the recent cases, where the re- 
sults obtained by the different analysts were very 
conflicting. On the other hand, even with un- 
skilled chemists, Reinsch’s test, when properly 
carried out, is thoroughly to be depended on, 
and is under ordinary circumstances more deli- 
cate than that of Marsh. Not the least of its 
advantages is the fact that it requires but a 
short time and the simplest apparatus only. 
Its value is well brought out by no less an 
authority than A. H. Allen, writing in the 
Chemical News. It is greatly to be hoped that 
the present agitation will result in placing 
the tests for arsenic on their proper relative 
basis. 
SOMETIME since attention was called in this 
column to the fact that in the examination of 
quite a number of canned goods, tin was found 
present in every instance. A paper on the 
same subject by F. Wirthle has appeared in the 
Chemiker Zeitung, dealing with canned meat, 
mostly beef. ‘The goods were from one to five 
years old, and in each case tin was found, and, 
as was also true of the experiments above re- 
ferred to by Cowan and the writer, only the 
