Polytechnic Association. 669 



disappears on placing the phosphorescent matter in any medium free 

 from oxygen. Phosphorescence commences soon after the death of 

 the animal, and when decomposition sets in it ceases. 



VII. Sponge Paper. 



This article, recently patented in France, is fabricated by adding 

 to ordinary paper pulp, evenly and finely divided sponge ; and by 

 mean's of the ordinary paper-making machinery the mixture is 

 worked into sheets of different thickness. As this paper absorbs a 

 great deal of moisture and holds it for a long time, it is capable of 

 important technical applications. In dressing wounds^ it has been 

 used with considerable advantage. 



Dr. L. Feuchtwanger stated that some years ago asbestus paper was 

 made in Baltimore for printing, which was used also for its incom- 

 bustible and absorbent qualities. 



VIII. To Calculate the Heating Power of Petroleum. 

 II. St. Clair Deville of France gives the following rule for estimat- 

 ing the calorific effects of a given sample of oil, which, although it 

 makes the theoretic amount a little larger than that found in practice, 

 is near enough to ascertain the relative values of oils as fuel. First, 

 the amount of carbon, hydrogen and oxygen contained in the sample 

 is found by analysis. Second, subtract from the hydrogen one-eighth 

 of the oxygen, then multiply the difference by 344.62, and add to the 

 product the quantity of carbon multiplied by 80.8, and this sum will 

 be the number of heat units in one kilogram. 



IX. Spectra of the Nitrogen Group of Elements. 

 M. Ditte has examined the spectra of nitrogen, phosphorus, arsenic 

 and antimony, produced by passing the electric spark through their 

 several chlorides, taking care to eliminate the bands known to result 

 from chlorine. The most interesting phenomenon noted by him was 

 that the spectra increase progressively from nitrogen to the antimony ; 

 they begin at points near the orange red, but the more refrangible 

 rays extend themselves more and more toward the violet in propor- 

 tion as the properties of the elements under examination approximate 

 to the metallic character. 



X. Contagious Epidemics. 

 M. Chauveau has laid before the French Academy of Sciences the 

 results of his researches on contagious epidemics. He had previously 

 shown that the contagion caused by virulent humors depends not on 



