PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 541 



2. Green Stars. — Nitrate l)aryta, 5; chlorate potash, 2; sulphur, 

 2; black SbSg. 



3. Lilac Stars. — Chlorate potash, 40; sulphur, 25; chalk, 20; 

 black CuO, 6. 



4. Purple or Blue Stars. — Chlorate potash, 42; pure nitrate 

 potash, 22; sulphur, 22; CuO, 10. 



With regard to the remaining receipts I am not able to state 

 whether they are original or not lit this distance of time; still, as 

 they are all well proved, I venture to send them, if they will not 

 take up too much room in your journal. 



5. White Stars. — Saltpetre, 16 ; sulphur, 4 ; black sulphide 

 antimony, 5. 



Blasting powder at 6d per lb., reduced to powder is meant in 

 the following receipts : 



6. Tail Stars. — Blasting powder, 8 ; sulphur, 8 -, saltpetre, 8 ; 

 'Coarse charcoal, 8. 



Charge for 2 oz. Rockets. — Blasting powder, 20 ; charcoal, <> ; 

 saltpetre, 4. A moderate amount of blasting powder for the head 

 to light and disguise the stars. 



Composition for Roman candles between the stars lying on 

 p'owder at Is. 3d. per lb. Saltpetre, 5; blast powder, li ; sul- 

 phur, 1 ; sand, 1. 



Spur Fire. — Saltpetre, 4^ ; sulphur, 2 ; finely powdered and 

 mixed, and then gently rubbed with lampblack, 1^; pack in cases 

 six inches long and three-quarters internal diameter. 



PiioroRTioN OF Oil in Various Seeds, &c. 

 jNIunch exhausted the materials with ether, and gives the fol- 

 lowing as the [)ercentages of oil in the various substances : 



Per cent. 



Sweet almonds 55.4 



Bitter almonds 52.0 



Poppy seed ._ 49.4 



Hemp seed „ 35.5 



Cacao _ 47.4 



Linseed ... ._ 29.6 



Mustard 31.8 



Croton seed ._ _ _. 43.4 



Castor seed 40.0 



Laurel berries _ 31.8 



Mace _ .. 25.5 



