250 
being the conditions, the wonder is, not that 
diamonds are found as big as one’s fist, but 
that they are not found as big as one’s head. 
The chemist arduously manufactures infini- 
tesimal diamonds, valueless as ornamental 
gems; but Nature, with unlimited temper- 
ature, inconceivable pressure and gigantic 
material, to say nothing of measureless 
time, produces without stint the dazzling, 
radiant, beautiful crystals Iam enabled to 
show you to-night.” 
Proressor Movreto, of Madrid, has in- 
vestigated the preparation of a strongly 
phosphorescent strontium sulfid. The pure 
compound shows no phosphorescence, but 
the presence of a small quantity of alkali 
seems necessary, and a trace of subnitrate 
of bismuth is of advantage. When the 
mass which has been strongly heated is 
very slowly cooled, it shows after the ac- 
tion of even very little light, a strong phos- 
phorescence. This property is lost on 
pulverization, but may be restored by long 
heating with starch. 
In the Zeitschrift fiir Angewandte Chemie 
Th. Bokorny gives the results of a study of 
the antiseptic action of various substances. 
A culture medium of half per cent. egg al- 
bumen or peptone, with one-tenth per cent. 
potassium phosphate, two-tenths per cent. 
magnesium sulfate and a trace of calcium 
chlorid was infected with the bacteria of 
decay, and after addition of the substance 
to be tested, placed for several days in an 
incubator. Among inorganic compounds 
silver nitrate and mercuric chlorid have 
about the same value, 0.002 %, killing all 
organisms in two days. The antiseptic 
limit with silver nitrate is 0.0002 %; with 
mercuric chlorid 0.001 to 0.0002 %. Cop- 
per sulfate is nearly as active, 0.005 % 
killing all organisms in twenty-four hours, 
and 0.001 % preventing decomposition. 
Zine sulfate 0.01 % kills infusoria in 
eighteen hours, but 0.1 % is not completely 
SCIENCE. 
[N. 8S. Vox. VI. No. 137. 
antiseptic, while cadmium sulfate toward 
algee and infusoria is weaker than the zine 
salt, but toward bateria stronger, 0.02 % 
being antiseptic. Lead acetate and nitrate 
in 0.1 % solution only delay decay, while it 
is prevented by the same strength of iron 
sulfate solution. The fluorids are not 
strong antiseptics, the limits being for hy- 
drofluorie acid 0.02 %, barium fluorid 0.3 
%, aluminum fluorid 0.1 %, calcium 
fluorid 0.03 %, ferric fluorid 0.06 %, mag- 
nesium fluorid 0.05 %. Ammonium fluorid 
0.1 % is without action, but sodium fluorid 
0.1 % is antiseptic; potassium fluorid is 
rather more active. J. L. H. 
NOTES ON ENGINEERING. 
A commirrex of the British Institution of 
Civil Engineers, appointed a year ago or 
more, have reported thé following recom- 
mendations on steam. engine efficiency, and 
they have been adopted by the Council: 
(1) That the statement of the economy of a steam- 
engine in terms of pounds of feed-water per I.HP. per 
hour is undesirable. 
(2) That for all purposes except those of a scientific 
nature it is desirable to state the economy of a steam- 
engine in terms of the thermal units required per 
I.HP. per hour (or per minute), and that if possible 
the thermal units required per brake HP. should also 
be given. 
(3) That for scientific purposes the thermal units 
that would be required by a perfect steam-engine 
working under the same conditions as the actual en- 
gine should also be stated. 
The proposed method of statement is applicable 
to engines using superheated steam as well as to 
those using saturated steam, and the objection to 
the use of pounds of feed-water, which contain more 
or less thermal units according to conditions, is obvi- 
ated, while there is no more practical difficulty in ob- 
taining the thermal units per I.HP. per hour than 
there is in arriving at the pounds of feed-water. 
For scientific purposes the difference in the thermal 
units per I.HP. required by the perfect steam-engine 
and by the actual engine shows the loss due to imper- 
fections in the actual engine. 
A further great advantage of the proposal is that 
the ambiguous term ‘efficiency’ is not required. 
Iy the contest which has now been so long 
