You can get Borax from BigGreenSmile here:
http://www.biggreensmile.com/search.aspx?q=Borax
Deb P's link takes you to a supplier of a borax
substitute called Dri-Pak - it is not a borate, it is sodium sesquicarbonate - so
there is NO borax in it.I quote from the manufacturers own site (
www.dri-pak.co.uk/cleaning-products/borax-substitute/):
"Sodium sesquicarbonate ..... It is gentler than Soda Crystals yet stronger than Bicarbonate of Soda" - which is great if you want to wash clothes (and even better for the supplier - who can buy it as soda and sell it cheaper than borax). It might even make some ants quite ill; but it will never get to the queen.
Try this search on Google: "sodium borate uk -substitute -phosphate" - it brings up various sites selling real borax. Prices vary a
LOT eg. between a totally mad £77 per kilo (in 50g packs) and a very reasonable £2.50 per kilo (in 25Kg packs)
The URL below is the latter supplier and also seems to have sensible prices for smaller quantities (£5.95 for 1Kg post free):
http://www.ebay.co.uk/itm/Borax-Sodium-Tetraborate-Decahydrate-99-9-Lab-Grade-500g-1KG-2KG-5KG-10KG-25KG-/321094621563?_trksid=p2141725.m3641.l6368Cheers.
PS. this one is interesting: an ebay site called "1 X 12kg Solubor DF- sodium borate correct boron deficiency carrots, swedes etc"(won't display its URL unless you log in) is selling at £3.30 per kg (in 12Kg packs) and the product is neutral pH - better for it's purpose (spraying) but not necessarily for ants.
http://www.borax.com/docs/product_pdfs_data/solubordf-2012.pdf makes interesting reading - a wide range of crops are susceptible to borate deficiency - including apples, carrots, caulis, celery, grapes, olives, red beet, sunflower, swede, turnip. It mentions cabbages, citrus, pears, potatoes, tomatoes as moderately susceptible.
So if the plants around your dead ants nest start growing better you know why...