TESTIMONY OF GEORGE F. BARKER. 207 



WEDNESDAY, December 27, 1876. 



Mr. PRENTICE read by stipulation the evidence of Prof. Geo. F. 

 Barker, taken in the case of John Joechter, tried Feb. 2, 1876. 



GEORGE F. BARKER, sworn : 



Q. You are a professor at Yale College ? A. I am not now. 



Q. You were? A. Yes, sir, I was. 



Q. What was your chair, and what is your present position ? 

 A. I had the chair of physiological chemistry, and I am now pro- 

 fessor of physics in the University of Pennsylvania. 



Q. What has been your professional experience ? A. My pro- 

 fession at Yale college was chemistry, and at Albany, doctor of 

 medicine. Since 1861, I have been a professor of chemistry up to 

 three years ago in various institutions. Three years ago I moved 

 to Pennsylvania, and took the chair of physics. My business of 

 course has been instruction. 



Q. Has the subject of pure cow's milk, and the method of testing 

 it, been under your inspection ? A. Yes, sir, it has occupied my 

 attention in discharging the duties of my chair, and the investiga- 

 tions I have made with a view to instruct my classes. 



Q. Have you lectured on the subject of milk ? A. I have. 



Q. And the literature upon the subject, the standard works, 

 you are acquainted with them ? A. Yes, sir. 



Q. You have heard the evidence of President Morton ? A. Yes, 

 sir. 



Q. And the lactometer, you consider it to be a hydrometer ? 

 A. Yes, sir. 



Q. How is it as giving the test of the specific gravity of liquids ? 

 A. It is a floating body, and a floating body floats in virtue of the 

 principle that a floating body thrown into a liquid will sink, until it 

 displaces its own weight of that liquid ; if the liquid be heavier than 

 water it will not have to sink as far ; the hydrometer is the generic 

 name of all instruments used for floatation ; the lactometer is used 

 for testing milk. 



Q. How do you determine the specific gravity of pure cow's 

 milk? A. By the lactometer. 



