t 



Processes in the Useful Arts. 173 



into a thin glass phial half a brick of Windsor soap, cut small, filling 

 the phial half full of alcohol, and placing it near the fire till the soap is 

 dissolved. This mixture put to cool in a mould gives the transparent 

 soa^jf^Archives des Decouvertes et des Inventions JSfouvelles. 



f 4. Mode of Preparing Emert/, By Mr Hawkins. 



Mr Hawkins, finding that the emery sold in the shops was totally insuf- 

 ficient for the purpose he had in view, namely, grinding two flat surfaces 

 of hard cast steel accurately, thought of applying a process he had seen for 

 washing over diamond dust, to emery ; and to be certain that his emery 

 was of good quality, he purchased of an emery-maker a quantity of those 

 small lumps or grains, which had longest withstood the action of the cast- 

 iron runners, and bed, and thus insured the hardness of the emery ; these 

 pieces were reduced to powder in a cast-iron mortar and then separated In- 

 to different portions by sieves. 



He then washed over the finest emery thus obtained, using oil instead 

 of water, as in the usual process, the former holding it in suspension for a 

 much longer time, and in this way he obtained a series of emeries which 

 had floated one, five, ten, fifteen, twenty, forty, and eighty minutes, 

 amongst which he found every variety necessary for his purpose, and keep- 

 ing them in boxes which were numbered according to the minutes they 

 had floated, he could at any time prepare more of any one kind. In this 

 way Mr Hawkins readily attained his object ; and ultimately by selecting 

 these grains of emery which resisted longest the action of the pestle and 

 mortar, he obtained some so hard as to be capable of cutting a ruby, when 

 employed instead of diamond dust. 



Mr Gill, by grinding Greek emery-stone between two flat and hard steel 

 surfaces, and washing off the lighter portions in oil, found that thos^ 

 which subsided in half a minute, when examined by a microscope, had 

 entirely resisted the friction, and were perfectly crystallized sapphires. — 

 {Tech, Rep.) 



5. Account of a Travelling Railway. By George Hunter. Esq. 



This ingenious invention, which is secured by patent, is represented in 

 Plate I. Fig. 11. which represents a waggon with its travelling railways b, 

 b. The small running wheels a a of the waggon have their peripheries 

 formed into a groove like a pully, which moves upon the round edge of the 

 same circumference of the circular railways b b. The peripheries of the 

 circular railways are covered with flat tire like ordinary wheels, and, from 

 their magnitude, they surmount obstacles more readily than the small 

 wheels a a would do. When an obstacle presents itself to the railway b b 

 they stand still, and the small wheels a a, rising on their inner circumfer- 

 ence, help them to surmount the obstacle. 



In order to confine the circular railways, Mr Hunter proposes to intro- 

 duce a guide arm and pully, as shown at c and d, Fig. 12. 



In justice to an ingenious individual, it is necessary to state, that almost 

 the same invention was submitted to the Society of Arts for Scotland on 

 the 27th December 1822, by Mr Heriot, carpenter at Duddingston, under 



