SCIENTIFIC SUMMARY. 
215 
which pour their poisonous refuse into the rivers. And so great i 3 the 
pollution of the water in some instances that when a light was applied to 
some of it dipped from the river at Bradford it actually burned. A man who 
accidentally tumbled into ariver and swallowed a mouthful of water died of the 
effects. The effluvia that rises from the Clyde produces sickness in summer 
time, and the Mersey emits an unbearable stench. The water of the Bourne 
is yellow as ochre and thick as glue, and the horse that drinks it dies. And 
all the rivers are more or less affected in the same way, and the fish that 
survive in some of the streams are so unwholesome that they are unfit for 
food, if not dangerous.” 
Respiration in Insects. — In a paper recently published (in the “Central- 
Blatt fur Agri. Chem.” Heft 6) Herr 0. Biitschli records some experiments 
which he conducted on the common cockroach ( Blatta orimtalis'). From 
these we learn that the liberation of carbonic acid was found to be directly 
proportional to the temperature. 
Variations in the Strength of a Muscle. — Professor F. E. Nipker pub- 
lishes a valuable paper on this subject in “ Silliman’s American Journal.” 
The conclusions drawn by the author are : — 1. After the relation of 
the strength of a muscle to the dynamical work of exhaustion has been 
determined, the strength at any time will be most accurately determined 
by measuring the dynamical work of exhaustion. On days when from any 
cause the muscles are temporarily weak, the strength as determined by the 
dynamometer, and the work of exhaustion with very heavy weights, is 
less. In exhaustion with lighter weights, however (5. kgr.), the exercise of 
the first part of the experiment appears to invigorate the muscle, and the 
influence of temporary weakness, due to errors in diet, or lack of exercise, 
or the oppressive atmosphere of the room, is eliminated. 2. The co- 
efficient of muscular power per square centimeter of section of the muscle,, 
is a quantity which varies greatly with different muscles, and with the same- 
muscle at different times ; or, in other words, the work which a muscle can 
perform depends not only upon its size but also upon its quality. 
The Body rendered Luminous by Phosphuretted Hydrogen. — The editors 
of “ Silliman’s American Journal ” state that Dr. Geo. Maclean, of 
Princeton, in a private communication to them, says : — u Several years 
ago, after spending a portion of the day in experimenting with this gas 
(PH 3 ), prepared from phosphorus and solution of potash, on retiring to 
bed I found my body quite luminous, from a glow like that of phosphorus 
exposure to the air. Either some of the gas escaping combustion, or the 
product of its burning, must have been absorbed into the system, and the 
phosphorus afterwards separated at the surface have there undergone 
eremecausis. I was conscious of no feeling that could be attributed to it, 
nor was my health apparently in any way affected by it.” Probably a repe- 
tition of the trial would reproduce the results observed by Dr. Maclean, 
which have apparently escaped notice heretofore because unsought. 
Unipolar JElectric Excitement of the Nerves. — The 11 Chemical News,” 
giving an account of a paper lately read before the French Academy, 
says that M. A. Chaveau states that for every subject whose nerves are 
in a perfect physiological state there is an electric value — commonly 
very weak, sometimes moderate, but rarely very high — which gives to the 
