768 TRANSACTIONS OP THE AMERICAN INSTITUTE. 



beside twenty per cent of water more than the Fray Bentos extract. 

 It is sold in jars with labels stating that the extract is prepared 

 " according to Liebig's process." It is extremely difficult, as 

 regards the extract of meat, the genuineness and purity of which 

 are not discoverable by the eye, to protect the public against 

 frauds; all manufacturers prepare their extract according to what 

 they call " Liebig's process," but since he had given only general, 

 and not special directions for the manufacturer, it so happens that 

 every one fills in the details after his own fashion, and the conse- 

 quence is that not one of these extracts is, in its composition, like 

 another. 



After some discussion on several of the items, Mr. McGuiness 

 submitted a diagram of his boiler, patented some time since, but 

 Avhich has not yet been put into practical operation. 



Voiceless Duck. 



Dr. W. Rowell exhibited the bronchial tubes of a duck which, 

 when alive, made no sound. He thought this inability to produce 

 sound was the result of disease. It was interesting as illustrating 

 a theory that in the larynx there are organs of speech, which like 

 those of hearing, once destroyed cannot be restored. 



Mr. Joseph A. Miller presented the following paper on 



Steam Boilers. 



The discussion before this association, on the cause of steam 

 boiler explosions, last winter, was not without beneficial results. 

 The foggy notions of theorists, attributing these explosions to 

 electricity suddenly generated, and explosive gases pro- 

 duced by decomposition, have been dispelled, and I hope also 

 the bugbear of low water, and the sudden formation of large 

 quantities of steam from small quantities of heated metal, 

 certainly not sufficient to raise the water teil degrees in tem- 

 perature. It is now a well proven fact that intelligence, vigi- 

 lance and honesty are the preventives, as ignorance, careless- 

 ness and cupidity are the real causes of boiler explosions. This 

 is true not only of the men in charge of the boilers, but of those 

 who design them and furnish the material, those who construct 

 them, and more often than all, those who use them. 



This question of steam boiler explosion is of such importance 

 to all men that I hope it will for more than one evening during 

 this winter occupy the attention and prominence it deserves. One 



