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This is the name latterly applied to the cotton mill which became prominent under the ownership of Philips and Lee (often referred to as Phillips & Lee). The mill was originally established by the Salford Engine Twist Company owned by George and John Philips, Peter Atherton, and Charles Wood.
1842 'More Cotton Mills Stopped in Manchester. —In addition to the mills before stated as having been wholly or partially closed, are now to added two others belonging to Mr. Guest, which were employed some or 600 hands. It may also be further stated, that the very extensive mills known as the Salford mills, are also standing, and that these, when fully occupied, cannot give employment fewer than 1,000 men, women, and children. The Salford mills are the property of the family of Mark Philips, Esq., M.P., but they had been worked of late by Messrs. Lambert, Hoolo, and Jackson.'
1843 'Large Sale: of Cotton Machinery and Mills. — A sale of cotton machinery took place on Wednesday last at the Salford-mills, Manchester, which concern for many years was under the able management of the late George Augustus Lee, Esq. This was the most extensive sale that has taken place in Manchester or the district for many years. As the owners of the property are amongst the wealthiest of the wealthy, so unusual a circumstance as the disposal of this property by public auction would seem to justify a passing remark or two, as tending to show the extreme depression of trade, as also some uncertain speculations, even when taken by parties supposed capable of forming a correct judgment, and who besides have boundless wealth at command. It is not quite three years since the owners of this property expended 25,000l. or 26,000l. on improvements — say two large steam engines and machinery of the most modern make, and resting, no doubt, satisfied that, by this large outlay, they would be enabled either to let or sell. Time, however, has shown that it has not been possible to do either the one or the other, though advertised for months, and though any eligible party might have had any accommodation consistent with certain but eventual payments. It is the opinion of competent judges, that if the three mills, steam-engines, &c, had also been unreservedly sold, that the entire would not have produced the amount expended two or three years since. There is no question but that 100,000l. was originally expended on this concern. There was not a single bidder for the mills and steam-engines — Liverpool Journal
1844 Advertisement: 'TO BE LET, for a term of years, with immediate possession, all those Capital FACTORIES, situate in Chapel Street, Salford, and known by the name of Salford Mills. These premises (the principal part which are fire-proof) are fitted with steam engines of 200 horses' power, and mill gearing of the best construction, by Messrs. Galloway. They are within five minutes' walk of the Manchester Exchange and have a most abundant supply of the best condensing water. Coals are clean. and first-rate hands plentiful —For particulars apply to T. M. FISHER, 21, Princess-street. Manchester.'
1844 Advertisement: 'Valuable Steam Engines, Boilers, Mill Geering. Hydraulic Press. Gas Apparatus, and other Effects, Salford Mills. By T. M. FISHER, on Thursday, the 2nd day of January, 1845, at the Mills, in consequence of their being converted into bonded warehouses: sale to commence punctually at eleven o'clock in the forenoon: TWO CAPITAL STEAM ENGINES, one 112, the other 102 horses' power, both made within the last three years, by Galloway, on the very best modern principle, and in excellent working condition; 13 waggon-shaped steam boilers: all the new mill geering; gas apparatus; wrought iron bucket water wheel; hydraulic press, 8 inch ram, with 1 and 2 inch geered pumps; wrought-iron steaming chest, reels, doubling frames, warping mills; tie counting-house fixtures, and capital mahogany winged bookcase, with drawers. May be viewed, and catalogues had, Monday and Tuesday, the 30th and 31st December, on the premises; or from the Auctioneer, 21, Princess-street, Manchester. 
1844 'The very extensive cotton mills, known as the Salford Mills, the property of Messrs. Phillips and Co., have been taken as a bonding warehouse for Manchester.'
Bancks and Co's Plan of Manchester, 1831 shows a long building, described as Salford Twist Mills, on a site containing a number of buildings, which may also have been part of the mill. One of the long narrow buildings on the site is shown as a gas works, and the shape would be consistent with Boulton & Watt's gas works. The site was 200 yards long, extending from the banks of the River Irwell to Chapel Street, and flanked by houses on Garden Street and Clowes Street. The 1849 O.S. maps  show little change in the layout, but the longest building is now marked 'Bonding Warehouse'. Goad's plan of 1893 shows a very similar layout, mainly in the ownership of Manchester Bonding Warehouse Co Ltd. The plan shows that the longest building had either 6 or 7 storeys, and the eastern face had about 44 windows for each floor.
A drawing in the Boulton & Watt Archive shows the layout of the gas plant. There appear to be six small retorts, with provision for a further two, and eight gasometers housed in a building. 
A Paper by William Murdoch in 1808 reported that there were 271 Argand burners and 633 cockspurs, requiring the production of 1250 cu ft of gas per hour. Based on 2 hours use per day, the daily consumption was 7 cwt of cannel coal in the retorts and about one-third of that quantity of cheaper common coal. The annual cost of cannel coal was £125, plus £20 for ordinary coal. However, the coke produced was sold for £93. The annual expenditure was £600, compared with an estimated £2000 for candles giving the same amount of light.  By-products included 4½ cwt of coke and 4¼ 'ale gallons' of tar. At that time there was no market for the ammoniacal liquor by-product.
An excellent account of the gas lighting system and its installation and problems is given in a recent book by Leslie Tomory. We learn that work commenced in late 1805, and in February 1806 guests were invited to see a demonstration of the lights in Lee's house (Lee had gas pipes laid under the street to his house, 100 yards away from the mill).