Potash in Sea Water. — Salt.-^Iron Boat. 371 



to be calcined in the drying oven until the sulphur is dissi- 

 pated and then transported into the pots for fusion. It gives 

 a superb glass. — Annals General de Sciences de Physique 

 Brussels, May, 1820. 



6. Portable Gas Lamjjs. 



These have been contrived by David Gordon of Edin* 

 burgh, and it is probable they will become quite common in 

 private families. 



They and made of strong copper, either spherical or cyl- 

 indrical, with hemispherical ends. The gas from coal or 

 oil is forced into them by a condensing pump, and is dis- 

 charged through a stop cock to the burner. A reservoir of 

 six inches diameter and nine inches high, filled with gas, 

 condensed by twenty-five atmospheres will burn six hours, 

 and afford a light equal to five candles of six to the pound. 

 If the gas be obtained from oil, such a lamp will burn 

 twelve hours. A sphere twelve inches in diameter will con- 

 tain sufficient gas for two argand lamps, equal to twelve 

 candles, burning six hours with coal gas or twelve hours with 

 gas from oil. Such lamps can be filled with very little ex- 

 pense or trouble, in every town where there is a public manu- 

 factory of coal gas. — Edin. Journal. 



7. Potash in Sea Water. 



Dr. Wollaston has ascertained the existence of potash in 

 sea water. It is in the state of sulphate and constitutes rath- 

 er less than goVo part of the water.— ^/cZem. 



8. Salt. 



The European salt mines and salt springs produce annu- 

 ally, as nearly as the estimate can be made, from twenty-five 

 to thirty millions of hundred weight of salt. — Idem. 



9. Iron Boat. 



The iron passage boat on the Forth of Clyde canal, con- 

 structed under the direction of Henry Creighton, Esq. for- 

 merly of Soho, has an extreme length of sixty feet, beam 



