114 ANNUAL OF SCIENTIFIC DISCOVERY. 



tearing or cutting around on three sides of the envelope, after which it may 

 be opened like the cover of a book, and the contents unfolded. The letter 

 thus goes on file carrying the envelope with it, as a testimony of the time and 

 place of mailing, and also of any misdirection, returning, &c., which often 

 might render such a matter of importance. 



INDIA RUBBER BUTTONS. 



A style of button for overcoats and general business clothing has been 

 introduced within the last two years, which grows more shiny w r ith age and 

 wear, and in its every quality seems to be an admirable button. It is made 

 from one of the Goodyear varieties of prepared rubber, and a manufactory is 

 now in operation in New Brunswick, which gives employment to some two 

 hundred hands, male and female. The buttons have until this season been 

 held at so high a price as to a great extent to prohibit their introduction, but 

 a material reduction has, we learn, been lately made, which bids fair to 

 render them the standard style for the class of clothing described. 



IMPROVED TOILET GLASS. 



An improved toilet glass exhibited at a recent exhibition of the London 

 Society of Arts, presents the peculiarity of reflecting the back of the head as 

 perfectly as it does the face, on one surface at the same time, thereby ena- 

 bling a lady to arrange her back hair with the greatest ease and precision. A 

 brass telescopic rod with a circular mirror suspended from it, is attached to 

 the top of an ordinary toilet glass by means of a thumb screw, and when the 

 rod is drawn out, the back of the head is at once reflected in the glass ; when 

 not required for use, the circular mirror can easily be placed back at the top 

 of the glass out of the way, so as not in the least to interfere with the ordinary 

 use of the glass. 



NEW WAY TO CLEAR A HOUSE OF RATS. 



A correspondent communicates a novel plan adopted by him to free his 

 house from rats, and which proved perfectly successful. His house had been 

 completely overrun by them, and he had tried every means to get rid of the 

 vermin but without success, until he hit upon the following expedient: 

 Kaising a small board hi the garret floor, he opened a communication between 

 the floor and ceiling beneath, which interior communicated with the spaces 

 between the side walls and the laths and plaster over the whole house. Into 

 this opening he placed a dish containing finely pulverized black oxide of 

 manganese, and poured over it a suitable quantity of strong hydrochloric 

 (muriatic) acid. The floor-board was then replaced. The effect of the chemi- 

 cal mixture of black oxide of manganese and hydrochloric acid is to disengage 

 slowly in the cold that most powerful, deodorizing, fumigating gas, chlorine. 

 In common with all gases, it gradually diffuses itself through the air, but 

 having a greater weight than atmospheric air, it accumulates at the low- 

 est levels. The tendency of the gas liberated, therefore, was to penetrate 



