I have some info on the washing soda if any one wants it. I have a pic of the box and several pics of mineral licks made with it. Let me know and I can just email you the pics. I also have this little tidbit of info.

What is Washing Soda?
.....Washing soda is Sodium Carbonate. Baking soda on the other hand is Sodium Bicarbonate. The two are not interchangeable in any way. If you cannot find it at your grocery store in the detergent isle, try asking for a special order. According to the good folks at Arm & Hammer, the upc code for the 55 ounce box is 33200-03020.