480 POPULAR SCIENCE MONTHLY. 



amendments to the Federal Constitution, have been placed on 

 terms of full legal right and equality. In no one respect does 

 this antagonistn more persistently manifest itself, than in opposi- 

 tion on the part of the white citizen voters to the exercise of free 

 and concurrent suffrage by the negro citizens. Yet, in view of 

 the restraints imposed by the Federal Constitution in respect to 

 political or legal discriminations against the negro race, any 

 change in the way of relief from the situation by State enactment 

 has been regarded as impracticable. A recent constitutional con- 

 vention of the State of Mississippi seems, however, to have at 

 last most ingeniously solved this difficult political problem, by 

 enacting that every citizen (white or black) of established age 

 shall pay a poll tax, the nonpayment of which shall exclude him 

 from voting ; and the collection of the tax out of exempt or non- 

 taxable property i. e., the possessions mainly of the poorer classes 

 was also denied. The intent of this provision was therefore 

 manifestly not to raise revenue, but to exclude negroes from vot- 

 ing by reason of nonpayment of the poll tax ; and by a like covert 

 purpose the commission of a list of petty crimes which white men 

 do not generally commit, such as thievery, arson, and obtaining 

 money under false pretenses, was also made a disqualification of 

 voting; while robbery, murder, and other robust crimes which 

 are practiced chiefly by white men were not included. 



" Within the field of permissible action under the limitations 

 of the Federal Constitution, the Mississippi convention swept the 

 circle of expedients to obstruct the exercise of the franchise for 

 the negro race." Eatliff vs. Beale, Mississippi Reports. 



IN the preface to the works of Jean Hey, the philosopher who nearly 

 three hundred years ago first suggested the cause of the increase in weight 

 of lead and tin when burned, M. Edouard Grimaux notices some of the 

 theories that have been put forth on the subject. Boyle explained the in- 

 crease by supposing that corpuscles of fire, passing through the walls of 

 the vessel in which the calcination took place, became fixed in the metal. 

 This theory was accepted by Stomberg, Lemery, and Nicolas Lefevre, and 

 was formulated by Lemery : " The pores of the lead are so disposed that the 

 corpuscles of the fire insinuate themselves among them; they remain 

 fastened and agglutinated in the pliant and intricate parts of the metal 

 without being able to escape from them, and add to its weight." Father 

 Cherubin, of Orleans, refuted this explanation by showing that glass was 

 not thus permeable; while Boerhaave, and afterward Boulduc, held that 

 there was no increase of weight in the calcination of metals. Bierne, in 

 1753, supposed that some rich and sulphurous acid coming from the flame 

 became fixed in the metal. Lavoisier declared the true cause the fixation 

 iu the metal of a part of the air in 1774, and a little while afterward, in 

 1775, Bayen called attention in the Journal de Physique to the existence of 

 Jean Key's Essays. 



