Mr. W. Baily on the Optical Properties of Starch. 123 



where r is necessarily positive. The expression for the vis 

 viva of Q will be precisely the same ; so that the equation of 

 vis viva for the system of two bodies will be 



r 



It thus appears that instead of the term depending on the 

 tensions being always positive, as the theory assumes, it will, 

 in the case just considered, be always negative ; so that if we 

 take the vis viva to represent the kinetic, and the term depend- 

 ing on the tensions the potential energy, it follows that it is the 

 difference, not the sum of the kinetic and potential energies which 

 in this case of motion will be constant. 



I apprehend that the same will hold in all cases where par- 

 ticles separated by finite intervals attract each other by forces 

 varying as some inverse power of the distance greater than 

 the first. A simple instance which any one may without dif- 

 ficulty try for himself is, where two equal bodies are moving 

 in the same straight line towards their common centre of 

 gravity. 



The theory of the Conservation of Force or Energy pro- 

 fesses to be founded on the principle of vis viva, of which, in 

 , the cases to which the latter applies, the principle of the con- 

 servation of energy purports to be merely a translation into 

 other terms. 



If the foregoing investigation be correct, it is evident that 

 the principle of the conservation of energy (in the form in 

 which it has been propounded) must involve a mistranslation 

 of the principle of vis viva, and that, instead of deriving sup- 

 port from, it is emphatically contradicted by the latter. 



6 New Square, Lincoln's Inn, 



XVI. On the Optical Properties of Starch. 

 By Walter Baily, Esq *. 



WHEN a grain of starch is seen under the microscope, it 

 generally exhibits a spot surrounded by a series of 

 faint lines forming closed curves. As the spot never occurs 

 on the apparent circumference of the grain, whatever position 

 the grain may take, the spot is obviously internal ; and as the 

 lines always surround it in the same manner, it follows that 

 they are not fixed markings but the foreshortened parts of a 

 series of transparent envelopes. In fact the grain consists of 

 a nucleus surrounded by coats. 



* Communicated by the Author. 



