Problem escaping ampersands in HTTP GET

[John Randall]

I am using an HTTP GET to add docs to Solr. All the docs load fine as long as 
none contain an ampersand. I get a syntax error when a doc contains a field, 
for example, with the phrase "Jack & Jill". 
 
How can I escape the ampersand so that the doc loads normally?
 
Thanks in advance.