What did Scout want to do with Jem's chemistry set in the novel To Kill A Mockingbird?

In Chapter 9, the Finch family gets together to celebrate Christmas at Finch's Landing. Uncle Jack buys Jem and Scout a pair of air rifles as Christmas presents. Scout explains to her cousin, Francis Hancock, what they got for Christmas and mentions that Jem also received a chemistry set. Scout tells Francis that it is a "real" chemistry set and that Jem is going to make invisible ink. Scout plans to write letters to Dill using the invisible ink.

Throughout the novel, Scout is found writing letters to her best friend Dill, who lives in Meridian, Alabama. On the first day of school, Scout gets caught by her teacher, Miss Caroline, while she is writing Dill a letter during a class activity. Dill's character is based on Harper Lee's childhood friend, Truman Capote. Similar to Dill, Truman Capote had a fascinating imagination and lived out of town. Like Dill, Truman would travel back home to Monroeville, Alabama to visit Harper Lee during the summers.