Yes, the uncountable form of the noun 'jam' could be a 'glass of jam' or a 'jar of jam'.
The noun 'jam' is a countable noun as a word for 'kinds' of (The jams we have are raspberry and peach.); a difficult situation (He's always getting into jams.); a number of vehicles blocking one another until they can barely move (This intersection often has jams); an occasion when equipment does not work because something prevents its parts from moving (That printer jams too often.)
"Traffic jam" is a concrete noun because it refers to a physical situation involving vehicles on the road. Concrete nouns are those that can be perceived through the senses, and a traffic jam can be seen and experienced. In contrast, abstract nouns represent ideas or concepts that cannot be physically touched or seen.
jam in the center of them and a glass of milk on the side
LeBron James
It depends upon the material of which the jar is made. If it is made of glass, as virtually all jam jars are, it is not biodegradable.
Jam starts with breaking glass (a window being smashed).
When I dropped the jar of jam, the immediate need was to clean up the broken glass, then to wash up the sticky jam.
Glass containers are good for jams and jellies because the glass won't react with the acidity of the fruit. Glass is also preferred since you can see the contents.
Example:- 454 g of orange jam contain 83 g sugar454 g jam---------------83 g sugar100 g jam----------------x g sugarx= 100x83/454= 18,18 g sugar (or 18 % sugar)
Put a glass or jam jar over it then slowly and carefully slide a card between the glass and the window. Holding the card to the glass, carry it outside and release it.
The statement "the rule is, jam tomorrow and jam yesterday—but never jam today" appears in Lewis Carroll's book "Alice Through the Looking-Glass." It is spoken by the White Queen to Alice during their conversation about time.
Blackcurrants contain high levels of acid that can react with iron, giving the jam a metallic taste and causing discoloration. Copper and glass pans do not react with the acid in the fruit, allowing the jam to retain its natural color and taste.
So that there are no organisms in the jars to feed off the jam and make it spoil when we put the jam in.