Formaldehyde does not form explosive mixtures with alcohol or xylene. 
However, there may be a reason for not combining them for disposal.

Your waste hauler should be consulted before combining any waste 
(even alcohol and xylene), as it may affect the manner in which the 
hauler ultimately disposes of it.  This in turn wll affect the cost 
to you, the generator.

Many disposal firms sell flammable waste to cement companies and 
other such industries for use as a fuel or fuel supplement in kilns 
and furnaces.  Aqueous contaminants lower the caloric value of the 
fuel and may render the waste unsuitable for this method of disposal. 
As the water content of the waste rises, it becomes more difficult to 
burn it in an incinerator and may even require the addition of 
expensive high-caloric fuel to destroy the material.  This becomes 
very expensive and is why, in many areas of the USA at least, the 
cost of disposing of formalin is so much higher than that of 
flammable solvents.

Because of cost and liability issues, having waste hauled away should 
be the choice of last resort.  Minimize the use of hazardous 
chemicals, recycle formalin and solvents, and replace with safer, 
more environmentally friendly reagents.

Dick

-- 
Richard W. Dapson, Ph.D.
Anatech Ltd.
Battle Creek, MI
800-ANATECH (800-262-8324)
email@anatechltdusa.com
Web address:  anatechltdusa.com