helium <-
structure(list(trial = 1:39, air = c(25L, 23L, 18L, 16L, 35L, 
15L, 26L, 24L, 24L, 28L, 25L, 19L, 27L, 25L, 34L, 26L, 20L, 22L, 
33L, 29L, 31L, 27L, 22L, 29L, 28L, 29L, 22L, 31L, 25L, 20L, 27L, 
26L, 28L, 32L, 28L, 25L, 31L, 28L, 28L), helium = c(25L, 16L, 
25L, 14L, 23L, 29L, 25L, 26L, 22L, 26L, 12L, 28L, 28L, 31L, 22L, 
29L, 23L, 26L, 35L, 24L, 31L, 34L, 39L, 32L, 14L, 28L, 30L, 27L, 
33L, 11L, 26L, 32L, 30L, 29L, 30L, 29L, 29L, 30L, 26L)), row.names = c(NA, 
-39L), class = c("tbl_df", "tbl", "data.frame"))