254 ANNUAL OF SCIENTIFIC DISCOVERY. 



gases -which it contained, and then hermetically sealing the filled bottles in 

 which it had been heated. When about to leave for Aberdeen, I opened a 

 bottle which had been closed by M. Maben, in February 1854; and after the 

 lapse of five and a half years, I found it as fresh as it was the first day. 

 Since then, M. de Pierre has greatly improved the discovery. The means 

 which he employs to effect the preservation is still heat; but heat applied in 

 some peculiar way, by manual dexterity, first discovered by a Swiss shepherd. 

 All that I am allowed to state is, that the effect of this new mode of applying 

 heat is, to remove a sort of diaspore, or animal ferment, which exists in milk 

 in very small quantity, and which is the real cause of its speedy decompo- 

 sition. When this species of ferment is removed, milk can be preserved for 

 an indefinite time in vessels not quite full, and consequently exposed to the 

 contact of rarefied air, a result which was not effected by the process of M. 

 Maben, as he completely expelled those gases which otherwise would have 

 rendered it sour." M. Moigno then exhibited a five-gallon vessel containing 

 milk, put up by M. Pierre's process, which he had brought from France to 

 Aberdeen, and which was afterwards opened and passed round. It was 

 found to be as natural, as pure, and as rich, as when first taken from the cow 

 in Normandy. 



ON THE USE OF SULPHATE OF BARYTES AS A PAINT. 



M. Kuhlmann, who was the first to apply this substance to house-painting, 

 has read a paper on the subject to the French Academy of Sciences. Sul- 

 phate of barytes is white, and is preferable both to white lead and to oxide 

 of zinc, not only on account of its durability, but also because it produces no 

 injurious effects upon the health of the workmen. To obtain it, M. Kuhl- 

 mann first deprives the natural carbonate of barytes, or witherite, of its 

 carbonic acid, by putting it in contact wirh the vapors of hydrochloric acid 

 issuing from the furnaces where sea-salt is decomposed for the purpose of 

 obtaining soda; after which he transforms it into a sulphate by the addition 

 of sulphuric acid. The sulphate is afterwards well washed, in order to 

 deprive it of every trace of the acid. The excess of water is then expelled, 

 either by pressure or swift rotation, and the paste which remains is put into 

 barrels for sale. Sulphate of barytes might be reduced to the form of dry 

 cakes like white lead, but it is preferable to keep it in the state of a paste, 

 because, when once dry, it cannot be again reduced so easily to a fine pow- 

 der, such as it was when first precipitated. It is used with great advantage 

 in the manufacture of paper-hangings, and has been successfully applied to 

 oil-painting, a coating of this paint being much more durable than any other 

 known. In examining the rubbish remaining after the demolition of one of 

 his furnaces for the transformation of chloride of barium, M. Kuhlmann 

 observed a green and blue substance, strongly resembling ultramarine; and, 

 in presenting a sample of it to the Academy, expressed his belief that it 

 would not be impossible to obtain artificial ultramarine from barytes. 



ACTION OF WATER ON GLASS. 



Pelouze has made some experiments on the decomposition of glass by 

 water. He finds, that while glass vessels in which water is boiled are but 

 very slowly attacked, powdered glass is decomposed with remarkable ease. 

 Thus, a pint flask, in which water was boiled for five days, lost scarcely a 

 decigramme; but when the neck of this flask was powdered, and boiled for 



