124 



THE POPULAR SCIENCE MONTHLY. 



is dried. When it is left to itself to dry, it 

 becomes shriveled, and has a bad appear- 

 ance. To guard against this, the following 

 process is adopted : An endless strip of pa- 

 per is passed by machinery first through a 

 vat of sulphuric acid, and then through 

 water, ammonia, and water again ; next a 

 cloth-covered roller deprives it of a portion 

 of the water, and finally it is pressed and 

 smoothed out by means of polished heated 

 cylinders. 



When properly manufactured, parch- 

 ment-paper has the same color and translu- 

 cency as animal parchment, its structure hav- 

 ing undergone a change from fibrous to cor- 

 neous. In point of cohesion and hygroscopi- 

 city, it is very much like common parchment. 

 When dipped in water, it becomes soft and 

 flaccid. It is impermeable to liquids, except 

 by dialysis. These qualities render parch- 

 ment-paper specially suitable for diplomas, 

 important papers, and in general for docu- 

 ments which it is desirable to preserve. As 

 compared with ordinary parchment, this 

 paper possesses the advantage that it is 

 very little liable to be attacked by insects. 

 Then, too, the characters inscribed on it 

 cannot be effaced without difficulty, and, 

 when effaced, cannot be replaced by oth- 

 ers — a perfect guarantee against all kinds 

 of falsification. By reason of its firm- 

 ness and durability, it is specially suited 

 for plans and drawings, particularly archi- 

 tectural drawings, which are much exposed 

 to moisture. Further, it might be used for 

 covering books ; or books, maps, etc., for 

 use in schools, could be printed on it, and 

 would be very durable. In place of animal 

 membrane, it is well suited for covering 

 jars of fruit, extracts, etc., as also for con- 

 necting the parts of distilling and other 

 apparatus. It furnishes excellent casings 

 for sausages. In surgery it is employed in- 

 stead of linen, oiled cloth, and gutta-percha, 

 for dressing wounds. 



Improvements in Street - Sprinkling.— 



An improved method of sprinkling streets 

 has been patented in England, by means of 

 which almost five-sixths of the expense of 

 watering may be saved. It appears that 

 the cost for labor in watering the streets of 

 London averages about $675,000 per an- 

 num, the cost of water being additional ; 



and it is contended that this work can be 

 done in a far more effectual and advanta- 

 geous manner, by a system of permanent 

 pipes, for an expenditure of less than 

 $15,000 per annum, while the interest upon 

 the plant necessary for the purpose would 

 not exceed $100,000. An experiment made 

 in Hyde Park warrants the conclusion that, 

 with the permanent system referred to, the 

 services of one man would be amply suffi- 

 cient for laying the dust over the whole of 

 the drives and rides in that park — a task 

 which at present engages twenty men, with 

 as many horses and carts. This area may 

 be taken as a seventy-fifth part of the total 

 road-way in London to be % watered ; and 

 hence we may conclude that about seventy- 

 five men, without either horses or carts, 

 could water the whole metropolis at the 

 cost for labor above stated. The city gov- 

 ernment of London is giving the matter 

 serious consideration ; and, if water is to 

 continue in use for the purpose of laying 

 dust on thoroughfares, the plan will doubt- 

 less be generally adopted on being proved 

 practicable. It is to be hoped, however, 

 that before long deliquescent salts will be 

 employed for this purpose rather than wa- 

 ter. The use of water in summer hastens 

 the decay of organic matter, and thus is 

 objectionable from a sanitary point of view. 

 Deliquescent salts will not alone lay the 

 dust, but will also disinfect the streets by 

 checking decomposition. 



French Association for the Advance- 

 ment of Science. — The French Association 

 met at Lyons, on August 21st, the opening 

 address being made by the president, Qua- 

 trefages. He traced the history of scien- 

 tific progress during the past hundred years, 

 and advocated the claims of science as an 

 important branch of general education. The 

 reports of the secretary and treasurer show 

 that the Association is in a flourishing state, 

 and that it has already, in its second year, 

 commenced to give material encouragement 

 to original investigators of science. The 

 most notable of the papers read in the gen- 

 eral meetings were the following : Dr. H. 

 Blanc, Surgeon-Major of the British Army, 

 on " The Means of guarding against Chol- 

 era : an Essay based on Practical Knowl- 

 edge of the Causes and Mode of Propaga- 



