I want to know the answer to the following question:
By 1838 how many companies beside Claridge's were offering asphalt?
All the background I'm provided with is that "In 1838, Claridge obtained patents in Scotland on 27 March, and Ireland on 23 April, and in 1851 extensions were sought for all three patents, by the trustees of a company previously formed by Claridge.". Is that enough to answer the question?