Scientific Lectures. 207 



in a kitchen, eighteen inches from the fire. The husband was tried 

 for murder, but acquitted on the supposition that the woman took 

 fire spontaneously, and was burned up. In another case, an old lady, 

 eighty years of age, unfortunately addicted to brandy-drinking, was 

 burned to a skeleton in her chair ; water was thrown upon her without 

 avail. There are no less than forty such cases on record. It has 

 been noticed that these cases generally occur in the winter, when the 

 party sits near the fire ; that often they are habitual topers, and 

 generally no other person is present. A morbid condition was supposed 

 to exist, and it was supposed that the alcohol of the breath took fire 

 from the burning wood, and communicated the flame to the body. 

 This finally received the attention of scientific men, and Liebig wrote 

 a long article on the subject, proving conclusively that it was utterly 

 impossible. An ordinary man, weighing 120 pounds, contains eighty 

 pounds of water, and it would be impossible to produce combustion 

 until long after death had been produced by- loss of moisture. The 

 idea that a body may be so saturated with alcohol as to be burned ud 

 by it, is refuted by the simple experiment of moistening a sponge 

 with alcohol, and setting it on fire. The moment the alcohol is 

 burned the flame disappears, and the sponge remains intact. 



Flame. 



Solids and liquids, when sufficiently heated, emit light. The light 

 which results from heating a solid is simply the glow of incandescence. 

 But when a burning body becomes gaseous we have a flame. The 

 flame is composed of gases at a high temperature. If we mix a gas 

 with a supporter of combustion we get an explosive mixture, as in 

 the case of oxygen and hydrogen, because combustion takes place 

 throughout the mass at once. We have a parallel case in mixing 

 solids ; gunpowder is a mixture of this kind. When we burn 

 carbon in the atmosphere, a considerable length of time elapses before 

 enough oxygen comes in contact with it to burn it up. But if we pul- 

 verize the charcoal and mix it with saltpeter, we have in the mass enough 

 oxygen to burn up the carbon. Gun-cotton is another example. In 

 gun-cotton we have the combustible and the supporter of combustion 

 side by side. Any disturbing cause which will cause the carbon and 

 the hydrogen of the cotton to unite with the oxygen produces an 

 explosion. It is simply instantaneous combustion. 



If we carefully scrutinize a flame we shall find that it is composed 

 of several layers. We have in the first place a dark cone in the 



