proceedings of the polytechnic association. 601 



"White Ants. 



The Admiralty are also seeking the best means of securing the destruc- 

 tion of the white ants introduced into Jamestown twenty years since from 

 the coast of Guinea. They have multiplied so as to injure every building 

 in the place, and have reduced some to such a state of riiin as to compel 

 the inhabitants to abandon them. Similar experience is related of the white 

 ant in India, where, if they once gain access to a house, their eradication is 

 impossible, unless the house is taken down and rebuilt. 



Mr. H, W. Bates, who had much experience respecting these insects in 

 South America, states that they do not attack houses, furniture, or boxes 

 made of hard wood called acapu. It was customary to protect articles of 

 softer wood by placing them on blocks of acapu. He found they could be 

 expelled by the use of the arsenical soap employed in preserving skins. 

 This compound — consisting of common soap, carbonate cf potash, and 

 white arsenic — is made into a lather and brushed over the articles to be 

 protected. This involves the dissemination of arsenic in the atmosphere, 

 and must be dangerous to the health of the inhabitants. The ravages of 

 the insects on the sleepers and wood-work of the East Indian railways 

 have been prevented by the use of creosote, which, however, has an odor 

 80 objectionable as to prevent its use in dwelling-houses. 



Blood Corpuscles. 



Prof. Beale, in a communication to the " Quarterly Journal of Microscopic 

 Science," says: "It is most remarkable that the red coloring matter of the 

 blood corpuscles of different animals should crystallize in different forms. 

 There are instances of animals closely allied to each other, the blood crys- 

 tals of which are quite distinct ; for example, the red coloring of the guinea 

 pig assumes the form of the tetrahedron, while that of the squirrel crystal- 

 lizes in six sided plates, and that of the hamster in rhomboidal crystals. 

 [The Hamster is an animal of the rat tribe, with large cheek pouches, 

 inhabiting the northern part of Europe.] The red matter is not living, but 

 results from changes occurring in the colorless living matter, just as cuticle 

 or tendon or cartilage, or the formed material of the living cell, results fi'om 

 changes occurring in the germinal matter of each of these cells. The col- 

 orless corpuscles, and these small corpuscles which are gradually under- 

 going conversion into red corpuscles, are living, but the old red corpuscles 

 consist of inanimate matter. 



Henna. 



This plant {Lawsonia inermis), long iised in Egypt as a cosmetic and 

 dye-stuff, has been prepared and introduced into commerce by Messrs. 

 Gillet and Tabourin, chemists, of Lyons, France. The active principle is a 

 peculiar kind of tannic acid, which they propose to call henna-tannic acid. 

 The dried leaves of the plant contain one half their weight of this sub- 

 stance. It imparts to silk different shades of black, which are beautiful 

 and permanent. 



Heat of the Sun's Kays. 



The observations on this subject by the late Dr. Otto Hagan have been 

 communicated to the Prussian Academy of Sciences. The most important 



