<P> Though the original Gorgie factory burned down in 1894, it was rebuilt the same year and remained operative until 1969, when production ceased and operations were transferred to the English sites which had been established at Harlesden in 1910 and Manchester in 1917 . The firm acquired the Edinburgh bakery of Simon Henderson & Sons in 1922 . McVitie & Price merged with another Scottish bakery company, Macfarlane, Lang & Co., Ltd, in 1948 to become United Biscuits Group . </P> <P> McVitie's brand products are now manufactured in five United Kingdom factories: the two former McVitie & Price factories in Harlesden and Manchester, a former Macfarlane, Lang & Co. factory named Victoria Biscuit Works in Glasgow, a former Carr's factory named The Biscuit Works established 1831 in Carlisle, and the McVitie's Cake Co. factory (formerly Riley's Toffee Works) in Halifax . </P> <P> McVitie & Price's first major biscuit was the McVitie's Digestive, created in 1892 by a new young employee at the company named Alexander Grant . The biscuit was given its name because it was thought that its high baking soda content served as an aid to food digestion . Grant was later to become managing director of the company, in 1923 he was the main benefactor in the establishing the National Library of Scotland giving an endowment of £ 100,000 . Grant donated a further £ 100,000 in 1928 to assist with the building of the National Library premises on George IV Bridge in Edinburgh . </P> <P> The McVitie's Chocolate Homewheat Digestive was created in 1925 . Over 71 million packets of McVitie's chocolate digestives are eaten in the United Kingdom each year, giving an average of 52 biscuits per second . HobNobs were launched in 1985 and a milk chocolate variant followed in 1987 . Launched in 1927, Jaffa Cakes were ranked the best selling cake or biscuit in the UK in 2012 . </P>

Where does the name digestive biscuit come from
find me the text answering this question