Page:Dictionary of National Biography, Second Supplement, volume 3.djvu/383

 at the Royal College of Chemistry and at Guy's and St. Bartholomew's hospitals. From 1865 to 1870 Sprengel held a post at the chemical works of Messrs. Thomas Farmer, Kennington, becoming a naturalised Englishman.

Sprengel was the first who described and patented in England a number of substances called safety explosives. They were of two kinds, liquid and solid. The liquid ones were, in general, solutions of nitrated hydrocarbons—chiefly nitrobenzene or picric acid in nitric acid, mixtures that could be exploded with considerable effect by a detonator. Sprengel allowed his patents to lapse, deriving no pecuniary benefit. Patents subsequently taken out by Hellhoff for the explosive ’Hellhoffite' and by Turpin for 'Panclastite' were essentially the mixtures suggested by Sprengel. In a paper read before the Chemical Society, 'On a New Class of Explosives which are Non-explosive during their Manufacture, Storage, and Transport' (Journal Chem. Soc. 1873), Sprengel described these substances and gave a list of combustible agents. The mixtures were to be exploded by fulminate detonators wrapped in dry guncotton, a method called by Sprengel 'cumulative detonation' (see Presidential Address,, Soc. Chem. Industry, 1883).

Sprengel's most notable achievement was his invention of a mercurial air-pump for the production of vacua of high tenuity by the fall of water or mercury in narrow tubes. This he described in his paper on 'Researches on the Vacuum' before the Chemical Society in 1865. The invention proved of immense service. In the hands of Bunsen, Graham, and Crookes the apparatus opened up departments of physical research of supreme interest; in those of Swan and Edison an era in regard to the incandescent electric light. 'It would be difficult indeed to enumerate the investigations which have owed their success to the invention of the Sprengel mercury pump' (, Presidential Address, Royal Society, 1906); for details of its practical applications, see Chemical News, 1870; The Times, 29 Dec. 1879 and 2 Jan. 1880; and The Development of the Mercurial Air-Pump, 1888).

Sprengel described to the Chemical Society other researches of practical bearing in 'On the Detection of Nitric Acid' (Journal, 1863); 'A Method of Determining the Specific Gravity of Liquids with Ease and Great Exactness' (1873); 'An Air-bath of Constant Temperature between 100° and 200° C (1873). To the 'Chemical News' he contributed the papers on ’Use of the Atomiser or Spray-producer in the Manufacture of Sulphuric Acid' (1875); 'Use of Exhaust Steam in the Production of Sulphuric Acid' (1887); and 'An Improvement in the Production of Sulphuric Acid' (1887).

Sprengel was elected a fellow of the Chemical Society in 1864, and served on the council (1871-5). He became F.R.S. on 6 June 1878. In 1893 the German emperor conferred on Sprengel the honorary title of royal Prussian professor.

At the latter part of his life Sprengel alleged that his rights of priority with regard to certain inventions and discoveries had been infringed, and his caustic letters to the publlc press detailing his grievances were reprinted in book form, with notes, as: 'The Hell-Gate Explosion in New York and so-called "Rackarock," with a few words on so-called Panclastite' (1886); 'Origin of Melinite and Lyddite' (1890); and 'The Discovery of Picric Acid (Melinite, Lyddite) as a Powerful Explosive, and of Cumulative Detonation, with its Bearing on Wet Guncotton' (1902; 2nd edit. 1903).

Sprengel died unmarried at 54 Denbigh Street, London, S.W., on 14 Jan. 1906, and was buried in Brompton cemetery.



SPROTT, GEORGE WASHINGTON (1829–1909), Scottish divine and liturgical scholar, born at Musquodoboit, Nova Scotia, on 6 March 1829, was eldest of five children of John Sprott, presbyterian minister there, by his third wife, Jane Neilson. Both his parents came from Wigtownshire. After early education in the colony Sprott entered Glasgow College in 1845 (see his John Macleod Memorial Lecture, Edinburgh 1902). One of his fellow students was (Sir) [q. v. Suppl. II], who consulted him about studying for the ministry. Sprott, besides taking a good place in his classes, and graduating B.A.