A HISTORY OF DURHAM 



none entirely satisfactory, are given for the col- 

 lapse of the Shields salt trade ; probably the discov- 

 ery of rock salt and the fact that the owners of 

 the salt-pans, who were often identical with the 

 owners of the collieries, found another use for 

 their inferior coal, when the demand for coke in- 

 creased, had a prejudicial eflFect on the trade. 

 Still the marvel is not that the trade ceased when 

 it did, but, considering the long and tedious process 

 employed, that it continued as long as it did. 



Before the trade was quite extinct, an import- 

 ant discovery had been made, 1858-62, by Mr. 

 John Vaughan (Messrs. Bolckow,Vaughan & Co.), 

 who, while boring for water, discovered on the 

 Yorkshire side of the Tees near Middlesbrough 

 a bed of rock-salt. No practical results followed 

 from the discovery ; and although Messrs. Bell 

 Brothers found salt on the Durham side at Port 

 Clarence in 1874 at a depth of 1,127 ^-j '"^ '^^^ 

 not until 1882 that the actual business of making 

 salt was begun. Three years later the Newcastle 

 Chemical Co. started works in connexion with 

 their chemical works on the Tyne, and about the 

 same time the Haverton Hill Salt Co., the first 

 to make salt for domestic purposes, began work, 

 and later the Greatham Salt Co., the most north- 

 erly of the works, started at Greatham. Once 

 started the development of the trade was rapid ; 

 in 1882 Durham only produced a little more than 

 3,000 tons of salt ; ten years later, including the 

 North Ormsby and Lackenby Works, 231,060 

 tons were being produced. The salt district ex- 

 tends over an area of 20 square miles on either 

 side of the Tees, and is estimated to contain 

 2,000,000,000 tons of salt, the average thickness 

 of the bed being from eighty to ninety feet. 

 Cheshire with its rock-salt near the surface has a 

 great advantage over Durham, where the bed is 

 at a depth of about i ,000 ft. ; on the other hand 

 the proximity of coal and a navigable river to a 

 certain extent counterbalance this disadvantage. 

 For the great quantity of coal used is a serious 

 item in the expense of working salt. 



Originally the boring down to the rock-salt 

 was done by the diamond boring process ; but the 

 substitution of the drilling system, as used in the 

 American oil districts, of derricks and free falling 

 * string of tools,' has been the means of saving time 

 and expense. The tube which is inserted is per- 

 forated three times, to admit the water from the 

 sandstone ; then when the salt bed is reached to 

 allow the water to flow over the rock-salt, and 

 again at the bottom of the salt bed so that the 

 brine can get admission to the inner pump tube. 

 The brine is then pumped to the surface, con- 

 veyed in pipes to the filter, and thence to large 

 pans, in which it is evaporated. The substitution 

 of iron and steel for lead pans is the only change 

 that has taken place in this part of the process 

 during the last 2,000 years. 



The vacuum process, which decreases the con- 

 sumption of coal by fifty per cent, and does away 



with the necessity of blocking and grinding, is 

 probably the method of the immediate future as 

 far as the works for the manufacture of fine salt 

 are concerned. The utilization of the surplus 

 heat from the blast furnaces decreases the expense 

 of those works in their neighbourhood, but only 

 the coarser salts can be made in this way. 



The salt-works at Clarence, where this method 

 is adopted, originally belonged to Messrs. Bell 

 Brothers. They are now worked by the Salt 

 Union. The waste heat from the blast furnaces 

 is conducted in flues under the salt-pans. The 

 gases from the furnaces are burnt under boilers to 

 raise the steam required to actuate the blowing 

 machinery, and the results of combustion pass 

 away from the end of the boilers at a high tem- 

 perature, a'rci? 1,400 Fahr. Between the chimney 

 which draws the gas from the furnaces under the 

 boilers and the boilers themselves, arrangements 

 are made to place the shallow salt-pans, and in 

 this way the heat which would otherwise be lost 

 is utilized. The temperature obtained is not high 

 enough nor under sufficient control to permit 

 the manufacture of the various kinds of salt ; what 

 is called technically chemical salt is the chief 

 product ; still a small quantity of fishery salt is 

 also obtained.^* 



The United Alkali Company have two sets of 

 salt-works on the Tees, one near Bellingham, the 

 other near Clarence, and both in the Haverton 

 Hill district, and the Tees Salt Company also 

 work salt at Haverton Hill. 



The fineness of the grain depends upon the 

 temperature at which the brine is evaporated. '^^ 

 By a curious coincidence, Greatham, near West 

 Hartlepool, where in the fourteenth century the 

 best English salt was made, is now the site of the 

 extensive Cerebos Salt Works. The business was 

 begun in 1894 for the manufacture of a very fine 

 table salt ; the invention is due to Mr. George 

 Weddel, the present managing director of the 

 company. In order to replace the phosphates 

 lost when food is cooked, he conceived the idea 

 of mixing in a definite proportion certain 

 phosphates with the salt. The invention met 

 with phenomenal success, and enlarged premises 

 soon became necessary. In 1 901 offices and 

 works were erected in Elison Place, Newcastle, 

 where the salt manufactured at Greatham is put 

 through the final refining processes. The phos- 

 phates, the addition of which differentiates Cere- 

 bos from all other salt, are here added, the salt is 

 put through various mills, sieves, and ovens, 

 weighed by automatic scales, and finally emptied 

 by automatic fillers into the cases, some of the 

 labour-saving devices in this department being due 

 to the ingenuity of Mr. Patterson, director of the 



" I am indebted to the courtesy of Messrs. Bell Bro- 

 thers for this account of the Clarence Salt Works. 



'^ MiJd/esirougi Sail Industry, by Richard Grigg. 

 Minutes of the Proceedings of the Institute of Me- 

 chanical Engineers, 2 Aug. I 893. 



300 



