PROFESSOR TRAILL ON THE COMPOSITION OF A NEW WRITING-INK. 425 



writing-ink, though it resists chemical agents. It is better suited for the pencil 

 than the pen ; it does not flow freely, and therefore is unfavourable to rapid 

 writing ; it does not sink sufficiently into the paper to resist rubbing ; and it may 

 be washed entu-ely from the surface of paper by the careful and repeated applica- 

 tion of a moistened pencil. 



2. Inks of carbon, incorporated with essential oils, promised to resist water. 

 One was several years ago proposed by Mr W. Close, which is formed by dis- 

 solving 24 grains of copal in 200 grains of Enghsh oil of lavender, and grinding 

 it with 4 grains of lamp-black. This ink resists Avater and several chemical 

 agents well ; but it cannot be used as a common TVTiting-ink ; for it does not flow 

 easily from the pen ; it sinks much in the paper, forming unseemly ragged lines. 



3. I tried many other resinous solutions in spirit and in oils ; but with no 

 better success. 



4. I obtained a better ink by mixing lamp-black with a solution of caoutchouc 

 in coal-tar-naphtha. This process forms an ink of a good body, which flows 

 pretty fi-eely from the pen ; but it spreads and sinks too deeply through the paper, 

 and is disagreeable from its penetrating and sickening odom*. 



4. I obtained a far more elegant solution of caoutchouc in an essential oil, 

 which spontaneously exudes from a South American tree, supposed to be a spe- 

 cies of Luui'us. This substance is fragi-ant, and readily dissolves caoutchouc ; but 

 the ink made with it has some of the disadvantages of the last sort, and would 

 be expensive, as the oil is a rai-e substance. It has hitherto only been brought 

 to us from British Guyana, under the Spanish name of Aceite de Sassafras, " oil 

 of sassafras," and has been highly extoUed as a remedy for rheumatism. 



Series VIII. Carbon with Animal Fluids. 



1. Lamp-black ground with the albumen of the egg united with difficulty; 

 the ink did not flow readily from the pen, and the characters appeai-ed coarse 

 and unequal. 



2. The white of the egg and Indian inks were not more successful. 



8. Milk and urine were also tried ; but though better than white of egg as 

 vehicles, the ink made with either of them was easQy effaced. 



4. Serum of blood was liable to similar objections as a vehicle for the car- 

 bon ; and I found that, 



5. Glue succeeded no better. 



Arts and Sciences, in the Royal Library at Paris. The finest would seem to be prepared from a lamp- 

 black, obtained by the combustion of vegetable oils, particularly that of Bignonia Tomentosa, mixed with 

 animal glue ; the greatest quantity is prepared by collecting the soot of pine wood, received in a cham- 

 ber 100 feet long, formed of paper pasted over bamboo, and divided into various compartments. The 

 lamp-black collected in the first compartment is coarse ; the finest is in the last compartment. The pre- 

 cautions used will shew how careful the Chinese are to obtain a lamp-black of a fine quality. 



