but are you absolutely sure?--I was once given petroleum ether when I ordered diethyl ether. Base did not dissolve.
Yes, absolutely certain that petroleum ether works. I have prepared quite a lot of cocaine freebase using petroleum ether. In the field, when preparing crude base from coca leaves, kerosene or gasoline is used to dissolve the base. The book Cocaine Handbook, an Essential Reference by David Lee has a number of great procedures and photographs covering preparation of freebase, crystallization of the hydrochloride, purity test etc. This book was originally published by AND/OR Press in 1981 but someone here recently said that it was still in print.
Cocaine Handbook: Post 253549 (not existing)
More on freebase: Post 184535 (https://www.thevespiary.org/talk/index.php?topic=9773.msg18453500#msg18453500)
(Ballistic: "Freebase", Methods Discourse)