on the Light emitted from various Bodies. 187 



Milk. 



Exper. 12. Human milk not being easily obtained, some 

 mackerel-light was incorporated, by agitation, with two ounces 

 of fresh cow's milk, which was thereby rendered finely lumi- 

 nous, and continued shining above 24 hours. Fresh cream also 

 retained some light ; though it was not so visible as with milk, 

 owing probably to its thickness. But, when either milk or 

 cream turn sour, they contract a very extinguishing property. 

 A quartof milk was kept five days, in a moderately cool place, 

 in the month of June; by that time, it was changed into a 

 mixture somewhat resembling curds and whey, that is, into a 

 soft smooth coagulated part, and a very thin one, both which 

 were acidulous. Some fine mackerel-light was mixed with two 

 ounces of each of them, in separate phials, and they extinguished 

 it immediately. 



1 



Bb 2 



