Scientific Intelligence. — Arts, ^' 203 



western coast of the peninsula of India, at least as far northward 

 as the boundaries of the province of Canara ; and there would 

 no doubt be sufficient to supply a considerable demand for this 

 valuable product. The piney tallow has been made known in 

 this country by Dr Babington, according to whose analysis 100 

 parts contain carbon 77, hydrogen 12 J, oxygen lOf , = 100.— 

 London Mechanic^'' Register. 



38. Indelible Writing Ink. — The following, recommended as 

 a process for preparing indelible writing ink, or at least as a sort 

 of approximation to it, is copied from the last number of the 

 Royal Institution Journal. " Let a saturated solution of indi- 

 go and madder in boiling water be made in such proportion as 

 to give a purple tint ; add to it from one-sixth to one-eighth of 

 its weight of sulphuric acid, according to the thickness and 

 strength of the paper to be used. This makes an ink which 

 flows pretty freely from the pen ; and when writing which has 

 been executed with it is exposed to a considerable but gradual 

 heat from the fire, it becomes completely black, the letters being 

 burnt in and charred by the action of the sulphuric acid. If 

 the acid has not been used in sufficient quantity to destroy the 

 texture of the paper, and reduce it to the state of tinder, the 

 colour may be discharged by the oxymuriatic and oxalic jicids 

 and their compounds, thojigh not without great difficulty. 

 When the full proportion of acid has been employed, a little 

 crumphng and rubbing of the paper reduces the carbonaceous 

 matter of the letters to powder, but by putting a black ground 

 behind them they may be preserved ; and thus a species of in« 

 delible writing ink is procured (for the letters are, in a manner, 

 stamped out of the paper), which might be useful for some pur- 

 poses, perhaps for the signature of bank notes." 



39. Lardner'^s Lectures on the Steam-Engine. — A short series 

 of popular lectures on the steam-engine, by Dr Lardner, the 

 Professor of Mechanical Philosophy in the London College, is 

 announced for publication. The author professes to have treat- 

 ed the subject in the most familiar style, and to have stripped 

 it so far of mathematical reasoning and technical phraseology, 

 as to render it at once intelligible and interesting to the general 

 reader. 



40. Carter's Patent Cast-iron Roofing.— 'Carter's patent cast- 

 iron roofing is represented by the patentee as well adapted for 



